Rounding number in arithmetic

1. A walk in the garden

2. 1
2
3
4
5 Round numbers to specified place value
Round numbers to significant figure
Round numbers to decimal places
Recognize the number of rounding in a given quantity
Rounding Numbers
At the end of this class you will be able to:
Limit mathematical results to the proper rounding

3. Rounding
4
5
6
7
8
0
1
2
3
9
10
A
B UP
DOWN

4. 50
60
70
80
90
10
20
30
40
100
0
UP
DOWN
4 9
Round 4961 to
the nearest ten
6 01
UTHTh

5. 80
65
90
67
8
60
61
10
63
69
70 UP
DOWN
4 9
Round 4961 to
the nearest ten
6 01
UTHTh

6. 80
65
90
67
8
60
61
10
63
69
70 UP
DOWN
4 9
Round 4961 to
the nearest ten
6 01
UTHTh

7. Rounding
4
5
6
7
8
0
10
2
3
9
10
A
B UP
DOWN

8. Rounding
4
5
6
7
8
0
1
2
3
9
10
A
B UP
DOWN
45
Round 451 to 2
significant figures
1
1 2 3
0

9. 80
65
90
67
8
60
61
10
63
69
70 UP
DOWN
4 9
Round 4961 to
the nearest ten
6 01
UTHTh

10. Rounding Numbers
Rounding means making a number simpler but keeping its value close
to what it was. The result isless accurate, but easier to use.

11. 6
Rounding Numbers to place value
6
unitsTenshundredThousads
1101001000
0 00

12. 6
Rounding Numbers to place value
6
unitsTenshundredThousads
1101001000
60 00

13. 6 48 5
Rounding Numbers to place value
6 48 5
unitsTenshundredThousands
1101001000

14. .6 9248 5
Rounding Numbers to place value
6 9248 5.
unitsTenshundredThousands tenths hundredths
1101001000
1
10
1
100
Round to the nearest ten

15. Rounding
4
5
6
7
8
0
1
2
3
9
10
A
B UP
DOWN
45
Round 452 to 2
significant figures
2
1 2 3
0

16. Rounding
4
5
6
7
8
0
1
2
3
9
10
A
B UP
DOWN
45
Round 455 to 2
significant figures
5
1 2 3
01
0

17. Rounding
94
95
96
97
98
90
91
92
93
99
100 UP
DOWN
49
Round 496 to 2
significant figures
6
1 2 3
01
0
0
0

19. Rounding
4 3
Round 4.31 to 1
decimal place
1
1 2
0. .34
.35
.36
.37
.38
.30
.31
.32
.33
.39
.40 UP
DOWN

20. Rounding
0 7
Round 0.758584
to 1 decimal place
5
1 2
0. 8584
3 4 5 6
.74
.75
.76
.77
.78
.70
.71
.72
.73
.79
.80 UP
DOWN
8

21. Decimal Places
• When we round to decimals, we start
counting as soon as we reach the decimal
point.
Round 17.46789 to 2 decimal places
1 decimal place 2 decimal places, this will
stay a 6 or go to a 7
depending on what the
next number is

22. 0.80.7
0.770.76
A) B)
C) D)
Round to 1 dp
0.7
1 2 3 4 5 6
6 858 4

23. 0.770.78
0.790.76
A) B)
C) D)
Round to 2 dp
0.7
1 2 3 4 5 6
6 858 4

24. 1.81.7
1.771.76
A) B)
C) D)
Round to 1 dp
1.768548

25. 3.0545
3.054 3.05446
3.0544
A) B)
C) D)
Round to 4 dp
3.054456

26. 2.8 2.74
3.02.7
A) B)
C) D)
Round to 1 dp
2.75

27. 13.4
13.0 14.0
13.3
A) B)
C) D)
Round to 1 dp
13.374

28. 26.5
25.0 26.6
26.0
A) B)
C) D)
Round to 1 dp
26.519

29. 23.1823.20
23.1723.10
A) B)
C) D)
Round to 2 dp
23.1782

30. 500.83
500.80
500.84
500.8A) B)
C) D)
Round to 2 dp
500.8251

31. 0.0040.00417
0.0050.00418
A) B)
C) D)
Round to 3 dp
0.00417

32. 5.00
4.99
4.98
4.90A) B)
C) D)
Round to 2 dp
4.999

33. 0.7300 0.7390
0.73990.7210
A) B)
C) D)
Round to 4 dp
0.72995

34. Rounding Numbers Significant place

35. Significant Figures
• When we round to significant figures, we start
counting as soon as we reach a number that is
not zero
Round 17.46789 to 2 significant figures
1 significant figure 2 significant figures, this
will stay a 7 or go to
a 8 depending on
what the next
number is
All the numbers after
will become zero
Round 17.46789 to 2 significant figures =17.00000 or
just 17

36. Rounding
4
5
6
7
8
0
1
2
3
9
10
A
B UP
DOWN
45
Round 451 to 2
significant figures
1
1 2 3
0

37. Rounding
34
35
36
37
38
30
31
32
33
39
40 UP
DOWN
Round
0.0000007341
to 2 Significant
figures
0.00000073
1 2 3 4
410
Identify the first significant
figureIdentify the second significant
figure
Keep the next number to the right of the second
significant figure

38. Rounding
04
05
06
07
08
00
01
02
03
09
10 UP
DOWN
Round
0.0000007341
to 2 Significant
figures
0.0000007
1 2 3 4
5
10
Identify the first significant
figureIdentify the second significant
figure
Keep the next number to the right of the second
significant figure
0

39. Round to 2 sf
Look at the next number
It’s less than 5 so we round down!
0.0000007
3
41
Identify the first significant
figure
1
00
2

40. Round to 2 sf
Look at the next number
It’s less than 5 so we round down!
0.0000007
3
41
Identify the first significant
figure
1
00
2

41. Round to 3 sf
Look at the next number
It’s less than 5 so we round down!
83 7 4 3 70 0 0
Identify the first significant
figure

42. Round to 2 sf
Look at the next number
It’s more than 4 so we round
up!
0 . 00 2 8 99

43. Round to 3 sf
Look at the next number
It’s more than 4 so we round
up!
0 . 00 2 8 790

44. Rounding to Significant Figures
Main
1. When you are rounding to decimal
places you start counting after the
decimal point, but with significant
figures you start counting at the
first non zero number
2.
i. 1000 1500 1460
ii. 200 160 157
iii. 40 37 37.1
iv. 6 6.1 6.09
v. 0.006 0.0064 0.00640
3.
a) 4.7
b) 0.058
c) 0.19
d) 540

45. Rounding to Significant
Figures (sig fig or s.f)
10 multiple choice
questions

46. 0.2
0.3
3
2A) B)
C) D)
Round-
0.23 to 1 s.f

47. 0.05
0.04 0.1
0.0
A) B)
C) D)
Round-
0.045 to 1 s.f

48. 600 620
700630
A) B)
C) D)
Round-
623 to 1 s.f

49. 50005300
60005330
A) B)
C) D)
Round-
5328 to 1 s.f

50. 0.0051
0.01 0.0050
0.00514
A) B)
C) D)
Round-
0.005136 to 2 s.f

51. 430426.21
420400.00
A) B)
C) D)
Round-
426.213 to 2 s.f

52. 3000300
3002.03010
A) B)
C) D)
Round-
3002.01 to 3 s.f

53. 1000
100 900
980
A) B)
C) D)
Round-
983.4 to 1 s.f

54. 0.0046
0.0045
0.00
0.004A) B)
C) D)
Round-
0.00456 to 2 s.f

55. 36300 4000
4530036000
A) B)
C) D)
Round-
36345.3 to 3 s.f

56. 6
Rounding Numbers to place value
6
unitsTenshundredThousads tenths hundredths
1101001000
1
10
1
100
0 0 0 0 0
.
.6 6 6