1. On Calculator Errors and Estimates
All decimal answers in this course are rounded off to three
significant digits. To obtain this,
start from the 1st nonzero digit,
round off to the third digit.
For example, 12.35 ≈12.4
0.001235 ≈ 0.00124.
3. On Calculator Errors and Estimates
Calculator Errors
As mentioned in the last section that when we calculate with a
machine we can make syntactic and/or semantic mistakes.
4. On Calculator Errors and Estimates
Calculator Errors
As mentioned in the last section that when we calculate with a
machine we can make syntactic and/or semantic mistakes. The
syntactic mistakes will be pointed out by the machine.
5. On Calculator Errors and Estimates
Calculator Errors
As mentioned in the last section that when we calculate with a
machine we can make syntactic and/or semantic mistakes. The
syntactic mistakes will be pointed out by the machine. But the
machine will execute semantic mistakes and return wrong
answers often without our knowledge.
6. On Calculator Errors and Estimates
Calculator Errors
As mentioned in the last section that when we calculate with a
machine we can make syntactic and/or semantic mistakes. The
syntactic mistakes will be pointed out by the machine. But the
machine will execute semantic mistakes and return wrong
answers often without our knowledge. When possible, take the
following steps to reduce semantic mistakes.
7. On Calculator Errors and Estimates
Calculator Errors
As mentioned in the last section that when we calculate with a
machine we can make syntactic and/or semantic mistakes. The
syntactic mistakes will be pointed out by the machine. But the
machine will execute semantic mistakes and return wrong
answers often without our knowledge. When possible, take the
following steps to reduce semantic mistakes.
* Have an estimate of the final outcome. If needed,
use the calculator to come up with an estimate.
8. On Calculator Errors and Estimates
Calculator Errors
As mentioned in the last section that when we calculate with a
machine we can make syntactic and/or semantic mistakes. The
syntactic mistakes will be pointed out by the machine. But the
machine will execute semantic mistakes and return wrong
answers often without our knowledge. When possible, take the
following steps to reduce semantic mistakes.
* Have an estimate of the final outcome. If needed,
use the calculator to come up with an estimate.
Example A.
a. Estimate √30, then find its calculator answer.
9. On Calculator Errors and Estimates
Calculator Errors
As mentioned in the last section that when we calculate with a
machine we can make syntactic and/or semantic mistakes. The
syntactic mistakes will be pointed out by the machine. But the
machine will execute semantic mistakes and return wrong
answers often without our knowledge. When possible, take the
following steps to reduce semantic mistakes.
* Have an estimate of the final outcome. If needed,
use the calculator to come up with an estimate.
Example A.
a. Estimate √30, then find its calculator answer.
Here is a short list of square roots.
A square–root list
10. On Calculator Errors and Estimates
Calculator Errors
As mentioned in the last section that when we calculate with a
machine we can make syntactic and/or semantic mistakes. The
syntactic mistakes will be pointed out by the machine. But the
machine will execute semantic mistakes and return wrong
answers often without our knowledge. When possible, take the
following steps to reduce semantic mistakes.
* Have an estimate of the final outcome. If needed,
use the calculator to come up with an estimate.
Example A.
a. Estimate √30, then find its calculator answer.
Here is a short list of square roots.
25 < 30 < 36, hence √25 < √30 <√36,
A square–root list
11. On Calculator Errors and Estimates
Calculator Errors
As mentioned in the last section that when we calculate with a
machine we can make syntactic and/or semantic mistakes. The
syntactic mistakes will be pointed out by the machine. But the
machine will execute semantic mistakes and return wrong
answers often without our knowledge. When possible, take the
following steps to reduce semantic mistakes.
* Have an estimate of the final outcome. If needed,
use the calculator to come up with an estimate.
Example A.
a. Estimate √30, then find its calculator answer.
Here is a short list of square roots.
25 < 30 < 36, hence √25 < √30 <√36, so
5 < √30 < 6.
A square–root list
12. On Calculator Errors and Estimates
Calculator Errors
As mentioned in the last section that when we calculate with a
machine we can make syntactic and/or semantic mistakes. The
syntactic mistakes will be pointed out by the machine. But the
machine will execute semantic mistakes and return wrong
answers often without our knowledge. When possible, take the
following steps to reduce semantic mistakes.
* Have an estimate of the final outcome. If needed,
use the calculator to come up with an estimate.
Example A.
a. Estimate √30, then find its calculator answer.
Here is a short list of square roots.
25 < 30 < 36, hence √25 < √30 <√36, so
5 < √30 < 6.
Since 30 is about half way between 25 and 36,
so we estimate that √30 ≈ 5.5, half way between 5
and 6. A square–root list
13. On Calculator Errors and Estimates
Calculator Errors
As mentioned in the last section that when we calculate with a
machine we can make syntactic and/or semantic mistakes. The
syntactic mistakes will be pointed out by the machine. But the
machine will execute semantic mistakes and return wrong
answers often without our knowledge. When possible, take the
following steps to reduce semantic mistakes.
* Have an estimate of the final outcome. If needed,
use the calculator to come up with an estimate.
Example A.
a. Estimate √30, then find its calculator answer.
Here is a short list of square roots.
25 < 30 < 36, hence √25 < √30 <√36, so
5 < √30 < 6.
Since 30 is about half way between 25 and 36,
so we estimate that √30 ≈ 5.5, half way between 5
and 6. In fact √30 ≈ 5.47722… ≈ 5.48 A square–root list
14. On Calculator Errors and Estimates
b. Estimate –4 – √27 , then find its calculator answer.
6
15. On Calculator Errors and Estimates
b. Estimate –4 – √27 , then find its calculator answer.
6
Using 5 ≈ √27, –4 – √27 ≈ –9,
16. On Calculator Errors and Estimates
b. Estimate –4 – √27 , then find its calculator answer.
6
Using 5 ≈ √27, –4 – √27 ≈ –9, so –4 – √27 ≈ 2 .
–3
6
17. On Calculator Errors and Estimates
b. Estimate –4 – √27 , then find its calculator answer.
6
Using 5 ≈ √27, –4 – √27 ≈ –9, so –4 – √27 ≈ 2 .
–3
6
The calculator answer is –4 – √27 ≈ –1.53 which is
6
the approximate, or the numeric answer.
18. On Calculator Errors and Estimates
b. Estimate –4 – √27 , then find its calculator answer.
6
Using 5 ≈ √27, –4 – √27 ≈ –9, so –4 – √27 ≈ 2 .
–3
6
The calculator answer is –4 – √27 ≈ –1.53 which is
6
the approximate, or the numeric answer.
If a whole Crazy Chicken cost $8.99 then it’s easier to use
$ 9 as an over or upper estimate.
19. On Calculator Errors and Estimates
b. Estimate –4 – √27 , then find its calculator answer.
6
Using 5 ≈ √27, –4 – √27 ≈ –9, so –4 – √27 ≈ 2 .
–3
6
The calculator answer is –4 – √27 ≈ –1.53 which is
6
the approximate, or the numeric answer.
If a whole Crazy Chicken cost $8.99 then it’s easier to use
$ 9 as an over or upper estimate. The real cost of two
chickens must be less than $18 (an upper estimate).
20. On Calculator Errors and Estimates
b. Estimate –4 – √27 , then find its calculator answer.
6
Using 5 ≈ √27, –4 – √27 ≈ –9, so –4 – √27 ≈ 2 .
–3
6
The calculator answer is –4 – √27 ≈ –1.53 which is
6
the approximate, or the numeric answer.
If a whole Crazy Chicken cost $8.99 then it’s easier to use
$ 9 as an over or upper estimate. The real cost of two
chickens must be less than $18 (an upper estimate).
The true answer must not be more than any upper estimate.
21. On Calculator Errors and Estimates
b. Estimate –4 – √27 , then find its calculator answer.
6
Using 5 ≈ √27, –4 – √27 ≈ –9, so –4 – √27 ≈ 2 .
–3
6
The calculator answer is –4 – √27 ≈ –1.53 which is
6
the approximate, or the numeric answer.
If a whole Crazy Chicken cost $8.99 then it’s easier to use
$ 9 as an over or upper estimate. The real cost of two
chickens must be less than $18 (an upper estimate).
The true answer must not be more than any upper estimate.
If a whole Crazy Chicken and a drink cost $11.08, then $11 is
a lower or under estimate.
22. On Calculator Errors and Estimates
b. Estimate –4 – √27 , then find its calculator answer.
6
Using 5 ≈ √27, –4 – √27 ≈ –9, so –4 – √27 ≈ 2 .
–3
6
The calculator answer is –4 – √27 ≈ –1.53 which is
6
the approximate, or the numeric answer.
If a whole Crazy Chicken cost $8.99 then it’s easier to use
$ 9 as an over or upper estimate. The real cost of two
chickens must be less than $18 (an upper estimate).
The true answer must not be more than any upper estimate.
If a whole Crazy Chicken and a drink cost $11.08, then $11 is
a lower or under estimate. The true cost of two chickens and
two drinks must be more than the lower estimate of $22.
23. On Calculator Errors and Estimates
b. Estimate –4 – √27 , then find its calculator answer.
6
Using 5 ≈ √27, –4 – √27 ≈ –9, so –4 – √27 ≈ 2 .
–3
6
The calculator answer is –4 – √27 ≈ –1.53 which is
6
the approximate, or the numeric answer.
If a whole Crazy Chicken cost $8.99 then it’s easier to use
$ 9 as an over or upper estimate. The real cost of two
chickens must be less than $18 (an upper estimate).
The true answer must not be more than any upper estimate.
If a whole Crazy Chicken and a drink cost $11.08, then $11 is
a lower or under estimate. The true cost of two chickens and
two drinks must be more than the lower estimate of $22.
The true answer must not be less than any lower estimate.
24. On Calculator Errors and Estimates
b. Estimate –4 – √27 , then find its calculator answer.
6
Using 5 ≈ √27, –4 – √27 ≈ –9, so –4 – √27 ≈ 2 .
–3
6
The calculator answer is –4 – √27 ≈ –1.53 which is
6
the approximate, or the numeric answer.
If a whole Crazy Chicken cost $8.99 then it’s easier to use
$ 9 as an over or upper estimate. The real cost of two
chickens must be less than $18 (an upper estimate).
The true answer must not be more than any upper estimate.
If a whole Crazy Chicken and a drink cost $11.08, then $11 is
a lower or under estimate. The true cost of two chickens and
two drinks must be more than the lower estimate of $22.
The true answer must not be less than any lower estimate.
A semantic error had occurred if the answer falls outside of
the range between a lower estimate an upper estimate.
25. On Calculator Errors and Estimates
b. Estimate –4 – √27 , then find its calculator answer.
6
Using 5 ≈ √27, –4 – √27 ≈ –9, so –4 – √27 ≈ 2 .
–3
6
The calculator answer is –4 – √27 ≈ –1.53 which is
6
the approximate, or the numeric answer.
If a whole Crazy Chicken cost $8.99 then it’s easier to use
$ 9 as an over or upper estimate. The real cost of two
chickens must be less than $18 (an upper estimate).
The true answer must not be more than any upper estimate.
If a whole Crazy Chicken and a drink cost $11.08, then $11 is
a lower or under estimate. The true cost of two chickens and
two drinks must be more than the lower estimate of $22.
The true answer must not be less than any lower estimate.
A semantic error had occurred if the answer falls outside of
the range between a lower estimate an upper estimate.
Here are some basic about estimating arithmetic calculation.
26. On Calculator Errors and Estimates
We note first that the answer for –3+5 can’t be more than 5 nor
be less than –3.
27. On Calculator Errors and Estimates
We note first that the answer for –3+5 can’t be more than 5 nor
be less than –3.
i. If P is positive and N is negative, then P+N is no more than P,
and no less than N.
28. On Calculator Errors and Estimates
We note first that the answer for –3+5 can’t be more than 5 nor
be less than –3.
i. If P is positive and N is negative, then P+N is no more than P,
and no less than N.
If there are more terms, the sum of all the positive terms is an
upper estimate and the sum of all the negative terms is a lower
estimate.
29. On Calculator Errors and Estimates
We note first that the answer for –3+5 can’t be more than 5 nor
be less than –3.
i. If P is positive and N is negative, then P+N is no more than P,
and no less than N.
If there are more terms, the sum of all the positive terms is an
upper estimate and the sum of all the negative terms is a lower
estimate. So for –23+2(2)2–3,
30. On Calculator Errors and Estimates
We note first that the answer for –3+5 can’t be more than 5 nor
be less than –3.
i. If P is positive and N is negative, then P+N is no more than P,
and no less than N.
If there are more terms, the sum of all the positive terms is an
upper estimate and the sum of all the negative terms is a lower
estimate. So for –23+2(2)2–3, +2(2)2 = 8 is an upper estimate
31. On Calculator Errors and Estimates
We note first that the answer for –3+5 can’t be more than 5 nor
be less than –3.
i. If P is positive and N is negative, then P+N is no more than P,
and no less than N.
If there are more terms, the sum of all the positive terms is an
upper estimate and the sum of all the negative terms is a lower
estimate. So for –23+2(2)2–3, +2(2)2 = 8 is an upper estimate
and –23–3 = –11 is a lower estimate.
32. On Calculator Errors and Estimates
We note first that the answer for –3+5 can’t be more than 5 nor
be less than –3.
i. If P is positive and N is negative, then P+N is no more than P,
and no less than N.
If there are more terms, the sum of all the positive terms is an
upper estimate and the sum of all the negative terms is a lower
estimate. So for –23+2(2)2–3, +2(2)2 = 8 is an upper estimate
and –23–3 = –11 is a lower estimate.
33. On Calculator Errors and Estimates
We note first that the answer for –3+5 can’t be more than 5 nor
be less than –3.
i. If P is positive and N is negative, then P+N is no more than P,
and no less than N.
If there are more terms, the sum of all the positive terms is an
upper estimate and the sum of all the negative terms is a lower
estimate. So for –23+2(2)2–3, +2(2)2 = 8 is an upper estimate
and –23–3 = –11 is a lower estimate.
Next we note that is 1/3 is smaller than 1/2,
34. On Calculator Errors and Estimates
We note first that the answer for –3+5 can’t be more than 5 nor
be less than –3.
i. If P is positive and N is negative, then P+N is no more than P,
and no less than N.
If there are more terms, the sum of all the positive terms is an
upper estimate and the sum of all the negative terms is a lower
estimate. So for –23+2(2)2–3, +2(2)2 = 8 is an upper estimate
and –23–3 = –11 is a lower estimate.
Next we note that is 1/3 is smaller than 1/2, i.e. when sharing a
pizza, more people–less pizza (per person), or that
less people–more pizza (per person).
35. On Calculator Errors and Estimates
We note first that the answer for –3+5 can’t be more than 5 nor
be less than –3.
i. If P is positive and N is negative, then P+N is no more than P,
and no less than N.
If there are more terms, the sum of all the positive terms is an
upper estimate and the sum of all the negative terms is a lower
estimate. So for –23+2(2)2–3, +2(2)2 = 8 is an upper estimate
and –23–3 = –11 is a lower estimate.
Next we note that is 1/3 is smaller than 1/2, i.e. when sharing a
pizza, more people–less pizza (per person), or that
less people–more pizza (per person).
ii. Given a fraction N of two positive numbers,
D
36. On Calculator Errors and Estimates
We note first that the answer for –3+5 can’t be more than 5 nor
be less than –3.
i. If P is positive and N is negative, then P+N is no more than P,
and no less than N.
If there are more terms, the sum of all the positive terms is an
upper estimate and the sum of all the negative terms is a lower
estimate. So for –23+2(2)2–3, +2(2)2 = 8 is an upper estimate
and –23–3 = –11 is a lower estimate.
Next we note that is 1/3 is smaller than 1/2, i.e. when sharing a
pizza, more people–less pizza (per person), or that
less people–more pizza (per person).
ii. Given a fraction N of two positive numbers,
D
{ if the denominator D increases, the new fraction is less.
if the denominator D decreases, the new fraction is more.
37. On Calculator Errors and Estimates
We note first that the answer for –3+5 can’t be more than 5 nor
be less than –3.
i. If P is positive and N is negative, then P+N is no more than P,
and no less than N.
If there are more terms, the sum of all the positive terms is an
upper estimate and the sum of all the negative terms is a lower
estimate. So for –23+2(2)2–3, +2(2)2 = 8 is an upper estimate
and –23–3 = –11 is a lower estimate.
Next we note that is 1/3 is smaller than 1/2, i.e. when sharing a
pizza, more people–less pizza (per person), or that
less people–more pizza (per person).
ii. Given a fraction N of two positive numbers,
D
{ if the denominator D increases, the new fraction is less.
if the denominator D decreases, the new fraction is more.
if the numerator N increases, the new fraction is more.
{ if the numerator N decreases, the new fraction is less.
38. On Calculator Errors and Estimates
Example D. a. Given an upper estimate of 4.8 + √34.8
6 + √2.1
Justify it.
39. On Calculator Errors and Estimates
Example D. a. Given an upper estimate of 4.8 + √34.8
6 + √2.1
Justify it.
Any fraction with a larger numerator, and/or a smaller
denominator when compared to 4.8 + √34.8 is more.
6 + √2.1
40. On Calculator Errors and Estimates
Example D. a. Given an upper estimate of 4.8 + √34.8
6 + √2.1
Justify it.
Any fraction with a larger numerator, and/or a smaller
denominator when compared to 4.8 + √34.8 is more.
6 + √2.1
Hence by replacing the numerator with a larger one
4.8 + √34.8
6 + √2.1
41. On Calculator Errors and Estimates
Example D. a. Given an upper estimate of 4.8 + √34.8
6 + √2.1
Justify it.
Any fraction with a larger numerator, and/or a smaller
denominator when compared to 4.8 + √34.8 is more.
6 + √2.1
Hence by replacing the numerator with a larger one
4.8 + √34.8 5
6 + √2.1 <
42. On Calculator Errors and Estimates
Example D. a. Given an upper estimate of 4.8 + √34.8
6 + √2.1
Justify it.
Any fraction with a larger numerator, and/or a smaller
denominator when compared to 4.8 + √34.8 is more.
6 + √2.1
Hence by replacing the numerator with a larger one
4.8 + √34.8 5+6
6 + √2.1 <
43. On Calculator Errors and Estimates
Example D. a. Given an upper estimate of 4.8 + √34.8
6 + √2.1
Justify it.
Any fraction with a larger numerator, and/or a smaller
denominator when compared to 4.8 + √34.8 is more.
6 + √2.1
Hence by replacing the numerator with a larger one
4.8 + √34.8 5+6
6 + √2.1 < 6
44. On Calculator Errors and Estimates
Example D. a. Given an upper estimate of 4.8 + √34.8
6 + √2.1
Justify it.
Any fraction with a larger numerator, and/or a smaller
denominator when compared to 4.8 + √34.8 is more.
6 + √2.1
Hence by replacing the numerator with a larger one and the
one with a small one, we obtain an upper estimate of 11/6.
4.8 + √34.8 5+6 11
6 + √2.1 < 6 = 6
45. On Calculator Errors and Estimates
Example D. a. Given an upper estimate of 4.8 + √34.8
6 + √2.1
Justify it.
Any fraction with a larger numerator, and/or a smaller
denominator when compared to 4.8 + √34.8 is more.
6 + √2.1
Hence by replacing the numerator with a larger one and the
one with a small one, we obtain an upper estimate of 11/6.
4.8 + √34.8 5+6 11
6 + √2.1 < 6 = 6
The correct answer must be smaller than this upper estimate.
46. On Calculator Errors and Estimates
Example D. a. Given an upper estimate of 4.8 + √34.8
6 + √2.1
Justify it.
Any fraction with a larger numerator, and/or a smaller
denominator when compared to 4.8 + √34.8 is more.
6 + √2.1
Hence by replacing the numerator with a larger one and the
one with a small one, we obtain an upper estimate of 11/6.
4.8 + √34.8 5+6 11
6 + √2.1 < 6 = 6
The correct answer must be smaller than this upper estimate.
If we obtained an answer of 2, we would know 2 is a
wrong answer because 2 is above the upper estimate of 11/6.
47. On Calculator Errors and Estimates
Example D. a. Given an upper estimate of 4.8 + √34.8
6 + √2.1
Justify it.
Any fraction with a larger numerator, and/or a smaller
denominator when compared to 4.8 + √34.8 is more.
6 + √2.1
Hence by replacing the numerator with a larger one and the
one with a small one, we obtain an upper estimate of 11/6.
4.8 + √34.8 5+6 11
6 + √2.1 < 6 = 6
The correct answer must be smaller than this upper estimate.
If we obtained an answer of 2, we would know 2 is a
wrong answer because 2 is above the upper estimate of 11/6.
Next we observe 24 < 34 or that for the positive power 4,
the larger base 3 produces larger outcome then with base 2.
48. On Calculator Errors and Estimates
Example D. a. Given an upper estimate of 4.8 + √34.8
6 + √2.1
Justify it.
Any fraction with a larger numerator, and/or a smaller
denominator when compared to 4.8 + √34.8 is more.
6 + √2.1
Hence by replacing the numerator with a larger one and the
one with a small one, we obtain an upper estimate of 11/6.
4.8 + √34.8 5+6 11
6 + √2.1 < 6 = 6
The correct answer must be smaller than this upper estimate.
If we obtained an answer of 2, we would know 2 is a
wrong answer because 2 is above the upper estimate of 11/6.
Next we observe 24 < 34 or that for the positive power 4,
the larger base 3 produces larger outcome then with base 2.
iii. Given bp where p > 0 is a fixed power and b > 0,
if b increases, the outcome increases (is larger),
49. On Calculator Errors and Estimates
Example D. a. Given an upper estimate of 4.8 + √34.8
6 + √2.1
Justify it.
Any fraction with a larger numerator, and/or a smaller
denominator when compared to 4.8 + √34.8 is more.
6 + √2.1
Hence by replacing the numerator with a larger one and the
one with a small one, we obtain an upper estimate of 11/6.
4.8 + √34.8 5+6 11
6 + √2.1 < 6 = 6
The correct answer must be smaller than this upper estimate.
If we obtained an answer of 2, we would know 2 is a
wrong answer because 2 is above the upper estimate of 11/6.
Next we observe 24 < 34 or that for the positive power 4,
the larger base 3 produces larger outcome then with base 2.
iii. Given bp where p > 0 is a fixed positive power and b > 0,
if b increases, the outcome increases (is larger),
if b decreases, the outcome decreases (is smaller).
50. On Calculator Errors and Estimates
b. Use a calculator to find a lower estimate of (1.87 + 0.08 ) 25.
√7
Justify the estimate.
51. On Calculator Errors and Estimates
b. Use a calculator to find a lower estimate of (1.87 + 0.08 ) 25.
√7
Justify the estimate.
0.08
The expression is of the form b25 where b = (1.87 + )
√7
52. On Calculator Errors and Estimates
b. Use a calculator to find a lower estimate of (1.87 + 0.08 ) 25.
√7
Justify the estimate.
0.08
The expression is of the form b25 where b = (1.87 + )
√7
Let’s replace b with a smaller number that is easier to execute.
53. On Calculator Errors and Estimates
b. Use a calculator to find a lower estimate of (1.87 + 0.08 ) 25.
√7
Justify the estimate.
0.08
The expression is of the form b25 where b = (1.87 + )
√7
Let’s replace b with a smaller number that is easier to execute.
By dropping the “extra bits” and keeping just the 1.8 we would
have an smaller and easier base to execute.
54. On Calculator Errors and Estimates
b. Use a calculator to find a lower estimate of (1.87 + 0.08 ) 25.
√7
Justify the estimate.
0.08
The expression is of the form b25 where b = (1.87 + )
√7
Let’s replace b with a smaller number that is easier to execute.
By dropping the “extra bits” and keeping just the 1.8 we would
have an smaller and easier base to execute.
Hence 1.825 ≈ 2,408,865 is a useful lower estimate.
55. On Calculator Errors and Estimates
b. Use a calculator to find a lower estimate of (1.87 + 0.08 ) 25.
√7
Justify the estimate.
0.08
The expression is of the form b25 where b = (1.87 + )
√7
Let’s replace b with a smaller number that is easier to execute.
By dropping the “extra bits” and keeping just the 1.8 we would
have an smaller and easier base to execute.
Hence 1.825 ≈ 2,408,865 is a useful lower estimate.
Now when we execute the original problem and the calculator
returns an answer that’s smaller than 2,408,865, then we know
one or more semantic mistakes had occurred.
56. On Calculator Errors and Estimates
b. Use a calculator to find a lower estimate of (1.87 + 0.08 ) 25.
√7
Justify the estimate.
0.08
The expression is of the form b25 where b = (1.87 + )
√7
Let’s replace b with a smaller number that is easier to execute.
By dropping the “extra bits” and keeping just the 1.8 we would
have an smaller and easier base to execute.
Hence 1.825 ≈ 2,408,865 is a useful lower estimate.
Now when we execute the original problem and the calculator
returns an answer that’s smaller than 2,408,865, then we know
one or more semantic mistakes had occurred.
57. On Calculator Errors and Estimates
b. Use a calculator to find a lower estimate of (1.87 + 0.08 ) 25.
√7
Justify the estimate.
0.08
The expression is of the form b25 where b = (1.87 + )
√7
Let’s replace b with a smaller number that is easier to execute.
By dropping the “extra bits” and keeping just the 1.8 we would
have an smaller and easier base to execute.
Hence 1.825 ≈ 2,408,865 is a useful lower estimate.
Now when we execute the original problem and the calculator
returns an answer that’s smaller than 2,408,865, then we know
one or more semantic mistakes had occurred.
However, because negative exponents means reciprocate,
58. On Calculator Errors and Estimates
b. Use a calculator to find a lower estimate of (1.87 + 0.08 ) 25.
√7
Justify the estimate.
0.08
The expression is of the form b25 where b = (1.87 + )
√7
Let’s replace b with a smaller number that is easier to execute.
By dropping the “extra bits” and keeping just the 1.8 we would
have an smaller and easier base to execute.
Hence 1.825 ≈ 2,408,865 is a useful lower estimate.
Now when we execute the original problem and the calculator
returns an answer that’s smaller than 2,408,865, then we know
one or more semantic mistakes had occurred.
However, because negative exponents means reciprocate,
we have 2–4 < 3–4 or that for the negative power –4, or that
the larger base 3 produces smaller outcome then with base 2.
59. On Calculator Errors and Estimates
b. Use a calculator to find a lower estimate of (1.87 + 0.08 ) 25.
√7
Justify the estimate.
0.08
The expression is of the form b25 where b = (1.87 + )
√7
Let’s replace b with a smaller number that is easier to execute.
By dropping the “extra bits” and keeping just the 1.8 we would
have an smaller and easier base to execute.
Hence 1.825 ≈ 2,408,865 is a useful lower estimate.
Now when we execute the original problem and the calculator
returns an answer that’s smaller than 2,408,865, then we know
one or more semantic mistakes had occurred.
However, because negative exponents means reciprocate,
we have 2–4 < 3–4 or that for the negative power –4, or that
the larger base 3 produces smaller outcome then with base 2.
iii. Given bp where p < 0 is a fixed negative power and b > 0,
60. On Calculator Errors and Estimates
b. Use a calculator to find a lower estimate of (1.87 + 0.08 ) 25.
√7
Justify the estimate.
0.08
The expression is of the form b25 where b = (1.87 + )
√7
Let’s replace b with a smaller number that is easier to execute.
By dropping the “extra bits” and keeping just the 1.8 we would
have an smaller and easier base to execute.
Hence 1.825 ≈ 2,408,865 is a useful lower estimate.
Now when we execute the original problem and the calculator
returns an answer that’s smaller than 2,408,865, then we know
one or more semantic mistakes had occurred.
However, because negative exponents means reciprocate,
we have 2–4 < 3–4 or that for the negative power –4, or that
the larger base 3 produces smaller outcome then with base 2.
iii. Given bp where p < 0 is a fixed negative power and b > 0,
if b increases, the outcome decreases (is smaller),
if b decreases, the outcome increases (is larger),
61. On Calculator Errors and Estimates
c. Use a calculator to find a upper estimate of (1.87 + 0.08 ) –5.
√7
Justify the estimate.
62. On Calculator Errors and Estimates
c. Use a calculator to find a upper estimate of (1.87 + 0.08 ) –5.
√7
Justify the estimate.
0.08
The expression is of the form b–5 where b = (1.87 + )
√7
63. On Calculator Errors and Estimates
c. Use a calculator to find a upper estimate of (1.87 + 0.08 ) –5.
√7
Justify the estimate.
0.08
The expression is of the form b–5 where b = (1.87 + )
√7
Let’s replace b with a smaller number that is easier to execute.
64. On Calculator Errors and Estimates
c. Use a calculator to find a upper estimate of (1.87 + 0.08 ) –5.
√7
Justify the estimate.
0.08
The expression is of the form b–5 where b = (1.87 + )
√7
Let’s replace b with a smaller number that is easier to execute.
By dropping the “extra bits” and keeping just the 1.8 we would
have an smaller and easier base to execute.
65. On Calculator Errors and Estimates
c. Use a calculator to find a upper estimate of (1.87 + 0.08 ) –5.
√7
Justify the estimate.
0.08
The expression is of the form b–5 where b = (1.87 + )
√7
Let’s replace b with a smaller number that is easier to execute.
By dropping the “extra bits” and keeping just the 1.8 we would
have an smaller and easier base to execute.
Hence 1.8 –5 ≈ 0.0529 when is a useful lower estimate.
66. On Calculator Errors and Estimates
c. Use a calculator to find a upper estimate of (1.87 + 0.08 ) –5.
√7
Justify the estimate.
0.08
The expression is of the form b–5 where b = (1.87 + )
√7
Let’s replace b with a smaller number that is easier to execute.
By dropping the “extra bits” and keeping just the 1.8 we would
have an smaller and easier base to execute.
Hence 1.8 –5 ≈ 0.0529 when is a useful lower estimate.
If a suspicious calculator outcome seems to be too large, try
finding an upper estimates that’s below the outcome to justify
our suspicion that the calculator answer was too large.
67. On Calculator Errors and Estimates
c. Use a calculator to find a upper estimate of (1.87 + 0.08 ) –5.
√7
Justify the estimate.
0.08
The expression is of the form b–5 where b = (1.87 + )
√7
Let’s replace b with a smaller number that is easier to execute.
By dropping the “extra bits” and keeping just the 1.8 we would
have an smaller and easier base to execute.
Hence 1.8 –5 ≈ 0.0529 when is a useful lower estimate.
If a suspicious calculator outcome seems to be too large, try
finding an upper estimates that’s below the outcome to justify
our suspicion that the calculator answer was too large.
Likewise if the outcome seems to be too small, try find a lower
estimate that’s more than the suspiciously small calculator
answer.
68. On Calculator Errors and Estimates
c. Use a calculator to find a upper estimate of (1.87 + 0.08 ) –5.
√7
Justify the estimate.
0.08
The expression is of the form b–5 where b = (1.87 + )
√7
Let’s replace b with a smaller number that is easier to execute.
By dropping the “extra bits” and keeping just the 1.8 we would
have an smaller and easier base to execute.
Hence 1.8 –5 ≈ 0.0529 when is a useful lower estimate.
If a suspicious calculator outcome seems to be too large, try
finding an upper estimates that’s below the outcome to justify
our suspicion that the calculator answer was too large.
Likewise if the outcome seems to be too small, try find a lower
estimate that’s more than the suspiciously small calculator
answer. For complicated calculation, we may estimate parts of
the expression to check and isolate input mistakes.
69. On Calculator Errors and Estimates
c. Use a calculator to find a upper estimate of (1.87 + 0.08 ) –5.
√7
Justify the estimate.
0.08
The expression is of the form b–5 where b = (1.87 + )
√7
Let’s replace b with a smaller number that is easier to execute.
By dropping the “extra bits” and keeping just the 1.8 we would
have an smaller and easier base to execute.
Hence 1.8 –5 ≈ 0.0529 when is a useful lower estimate.
If a suspicious calculator outcome seems to be too large, try
finding an upper estimates that’s below the outcome to justify
our suspicion that the calculator answer was too large.
Likewise if the outcome seems to be too small, try find a lower
estimate that’s more than the suspiciously small calculator
answer. For complicated calculation, we may estimate parts of
the expression to check and isolate input mistakes. And finally,
When in doubt, insert ( )’s.
70. Power Equations and Calculator Inputs
No calculator for part A, B and C.
Exercise A. Estimate the following expressions. Find an upper
estimate and a lower estimate. Justify.
1. √7 2. √10 3. √15 4. √29 5. √47 6. √73
7. √17 + √5 8. √37 +√7 9. √24.5 –√4.2 10. √84.3 –√65.8
Exercise B. Find the positive–term total as an upper estimate
and the negative–term total as a lower estimate. Justify.
11. –2 + 6 – 3 – 11 + 14 12. –2 –(–7) – 2 + 15 + 3
13. 42 – 62 – 23 + 2 14. (–2)(–3) – 4 +10 – 32
15. –22 + 26 – 32 16. –2*33 – 42 + 4*23
17. –4(–2)2 + 6 –(–3)2 18. (–2)*(–3)3 – 42 – 4*(2)3
Exercise C. Estimate the following expressions. Find an upper
estimate and a lower estimate. Justify.
19. 1 + √10 20. –2 – √17 21. –5 + √24
2 3 3
–5.3 – √17.1
22. –√14 + √67 6.8 + √24.8
23. 6 – √4.1 24. 1.1 + √4.1
5
71. Power Equations and Calculator Inputs
Exercise D. Use a calculator to find lower estimates by using a
smaller positive base.
25. (3.11 + √4.12)5 26. (14.2 – √8.77)3 27. (√50.2 + 2.07)4
8.13 6 29. (√102.8 – 0.3 )7 30. (–√3.9 – √8.9)5
28. (√82.8 + √4.2 )
√9.04
Exercise F. Use a calculator to find upper estimates by using a
larger positive base.
31. (2.91 + √8.92)5 32. (9.89 – √4.11)3 33. (√47.8 + 1.97)6
7.93 7 8.9 8.9
34. (√80.8 + √17 ) 35. (√24.8 + √9.1 )4 36. (√24.8 + √9.1 )4
Exercise G. Use a calculator to find lower estimates by using
larger positive base.
37. (2.91 + √8.92)–5 38. (9.89 – √4.11)–3 39. (√47.8 + 1.97)–6
Exercise H. Use a calculator to find upper estimates by using a
smaller positive base.
40. (3.11 + √4.12)–5 41. (14.2 – √8.77)–3 42. (√50.2 + 2.07)–4