The document discusses rounding decimals to a given place value by looking at the digit in the place to the right. If the digit is 4 or less, round down. If the digit is 5 or greater, round up. Examples are provided of rounding decimals to the hundredths, tenths and ones place. The document also discusses rounding very small numbers to the place value of the leading digit, which is the first non-zero digit reading from left to right. Examples of rounding decimals to the leading digit are given.

1. 3.4 Rounding Decimals
Friday, October 1, 2010

2. For you notebook (copy
this):

3. For you notebook (copy
this):
Rounding Decimals: to round a decimal to a given
place value, look at the digit in the place to the
right.

4. For you notebook (copy
this):
Rounding Decimals: to round a decimal to a given
place value, look at the digit in the place to the
right.
If the digit is 4 or less, round down.

5. For you notebook (copy
this):
Rounding Decimals: to round a decimal to a given
place value, look at the digit in the place to the
right.
If the digit is 4 or less, round down.
If the digit is 5 or greater, round up.

6. Rounding Decimals with
a number line

7. Rounding Decimals (write
these examples in your notebook.)

8. Rounding Decimals (write
these examples in your notebook.)
Round the decimal to the place value of the
bolded digit.

9. Rounding Decimals (write
these examples in your notebook.)
Round the decimal to the place value of the
bolded digit.
3.23 ------> 3.2, The digit to the right of 2 is
3, so round down.

10. Rounding Decimals (write
these examples in your notebook.)
Round the decimal to the place value of the
bolded digit.
3.23 ------> 3.2, The digit to the right of 2 is
3, so round down.
6.485 ------> 6.49, The digit to the right of 8 is
5, so round up.

11. Rounding Decimals (write
these examples in your notebook.)
Round the decimal to the place value of the
bolded digit.
3.23 ------> 3.2, The digit to the right of 2 is
3, so round down.
6.485 ------> 6.49, The digit to the right of 8 is
5, so round up.
2.83619 -----> 2. 836, The digit to the right of
the 6 is 1, so round down.

12. Rounding Decimals (write
these examples in your notebook.)
Round the decimal to the place value of the
bolded digit.
3.23 ------> 3.2, The digit to the right of 2 is
3, so round down.
6.485 ------> 6.49, The digit to the right of 8 is
5, so round up.
2.83619 -----> 2. 836, The digit to the right of
the 6 is 1, so round down.
5.961 -----> 6.0, The digit to the right of 9 is 6,
so round up. This causes the 5 to become a 6.

13. Now you try:
Round to the decimal as specified:
5.29 (nearest tenth)
7.096 (nearest hundredth)
6.48 (nearest one)
3.9876 (nearest thousandth)

14. Check your answers:
Round to the decimal as specified:
5.29 (nearest tenth) 5.3
7.096 (nearest hundredth) 7.10
6.48 (nearest one) 6
3.9876 (nearest thousandth) 3.988

15. Write this in your
notebook:
Rounding Small Numbers: You can round a very
small number to the place value of its leading
digit to help make it easier to understand. In a
decimal, the leading digit is the first nonzero digit
as you read from left to right.

17. Rounding to the Leading Digit (you do
not need to copy this)

18. Rounding to the Leading Digit (you do
not need to copy this)
A guitar was created that is 0.0003937 inch long. Round the
length of the guitar to the place value of the leading digit.

19. Rounding to the Leading Digit (you do
not need to copy this)
A guitar was created that is 0.0003937 inch long. Round the
length of the guitar to the place value of the leading digit.
To Solve: The first nonzero digit as you read 0.0003937
from left to right is 3 and it is in the ten-thousandths
place. You should round the digit to the nearest ten
thousandth.

20. Rounding to the Leading Digit (you do
not need to copy this)
A guitar was created that is 0.0003937 inch long. Round the
length of the guitar to the place value of the leading digit.
To Solve: The first nonzero digit as you read 0.0003937
from left to right is 3 and it is in the ten-thousandths
place. You should round the digit to the nearest ten
thousandth.
Because 9 is to the right of the ten-thousandth’s place,
round 3 up to 4.

21. Rounding to the Leading Digit (you do
not need to copy this)
A guitar was created that is 0.0003937 inch long. Round the
length of the guitar to the place value of the leading digit.
To Solve: The first nonzero digit as you read 0.0003937
from left to right is 3 and it is in the ten-thousandths
place. You should round the digit to the nearest ten
thousandth.
Because 9 is to the right of the ten-thousandth’s place,
round 3 up to 4.
Answer the length rounded to the leading digit is
0.0004 inch.

22. Try these (in your notebook)
Round the decimal to the leading digit)
0.058
0.0091
0.0952
0.006192

23. Check your answers.
Round the decimal to the leading digit)
0.058 0.06
0.0091 0.009
0.0952 0.10 (you don’t have to have the last 0)
0.006192 0.006

24. When you finish this
slideshow:
Take the section quiz (as practice) on
classzone.com. Go to assessments, then click on
section quizzes. Then click on 3.4 Rounding
Decimals.
Then play the animated math game on
classzone.com. Go to animated math. Then click
on Chapter 3: Comparing, Ordering and Rounding
Decimals.