Lesson 6-Math 5 -W6Q1_Rounding Off Decimals

1. Rounding Decimals

2. 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.

3. EXAMPLE 1 Using a Number Line to Round
Use a number line to round 3.87 to the nearest
tenth.
ANSWER
The decimal 3.87 rounds up to 3.9.

4. GUIDED PRACTICE
ANSWER
The decimal 1.3 rounds down to 1.
GUIDED PRACTICE for Example 1
Use a number line to round the decimal as specified.
1.) 1.3 (nearest one)
The decimal 1.3 is closer to 1 than to 3
1 1. 1 1. 2 1. 3 1. 4 1. 5 1. 6 1. 7 1. 8 1.9 2.0

5. GUIDED PRACTICE
ANSWER
The decimal 2.8 rounds up to 3.
Use a number line to round the decimal as
specified.
2.) 2.8 (nearest one)
The decimal 2.8 is closer
to 3 than to 2
2.2 2.3 2. 4 2. 5 2. 6 2. 7 2. 8 2. 9 3.0

6. GUIDED PRACTICE
The decimal 3.74 is closer to 3.7 than to 3.8
ANSWER
The decimal 3.74 rounds down to 3.7.
Use a number line to round the decimal as
specified.
for Example 1
3.) 3.74
3. 7
hundredth
3. 8 3. 9
3. 6
(nearest tenths)
tenths

7. GUIDED PRACTICE
The decimal 3.86 is closer to 3.9 than to 3.8
ANSWER
The decimal 3.86 rounds up to 3.9.
Use a number line to round the decimal as
specified.
4.)3.86
3. 7 3. 9 4. 0
(nearest tenth)
hundredth
3. 6
tenths
3. 8

8. Rounding Decimals
Round the decimal to the place value of
the yellow digit.
⚫3.23
⚫6.485
⚫2.83619
⚫ 5.961
⚫------> 3.2, The digit to the right
of 2 is 3, so round down.
⚫------> 6.49, The digit to the right of 8
is 5, so round up.
⚫-----> 2. 836, The digit to the right
of the 6 is 1, so round down.
-----> 6.0, The digit to the right of 9 is 6, so
round up. This causes the 5 to become a 6.

9. 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)

10. 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

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

12. 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

13. Assignment:
⚫Answer no. 1-20 on page 40