4-2 Adding and Subtracting Decimals
Today I will add and subtract decimals.
Course 2
4-2 Adding and Subtracting Decimals
66.8
+ 4.0
70.8
Use zero as a placeholder so that
both numbers have the same number
of digits after their decimal points.
Add each column just as you would
add integers.
Line up the decimal points.
Course 2
4-2 Adding and Subtracting Decimals
Additional Example 1A: Adding Decimals
Add. Estimate to check whether the answer is
is reasonable.
A. 4.55 + 11.3
4.55
+ 11.30
15.85
Line up the decimal points.
Use zero as a placeholder.
Add.
Estimate
5 + 11 = 16 15.85 is a reasonable answer.
Course 2
4-2 Adding and Subtracting Decimals
Additional Example 1B: Adding Decimals
Add. Estimate to check whether the answer is
is reasonable.
B. 6.44 + 16
6.44
+ 16.00
22.44
Line up the decimal points.
Use zeros as placeholders.
Add.
Estimate
6 + 16 = 22 22.44 is a reasonable answer.
Course 2
4-2 Adding and Subtracting Decimals
Try This: Example 1A
Add. Estimate to check whether the answer is
is reasonable.
A. 6.78 + 13.2
6.78
+ 13.20
19.98
Line up the decimal points.
Use zero as a placeholder.
Add.
Estimate
7 + 13 = 20 19.98 is a reasonable answer.
Course 2
4-2 Adding and Subtracting Decimals
Try This: Example 1B
Add. Estimate to check whether the answer is
is reasonable.
B. 4.21 + 34
4.21
+ 34.00
38.21
Line up the decimal points.
Use zeros as placeholders.
Add.
Estimate
4 + 34 = 38 38.21 is a reasonable answer.
Course 2
4-2 Adding
Insert Lesson
and Subtracting
Title HereDecimals
Lesson Quiz
Add.
1. 6.98 + 14.27 21.25
Subtract.
2. 6.72 – 4.16 2.56
3. 24 – 3.8 20.2
4. Renee finished her first lap in the 200 m freestyle
event in 28.76 seconds. She completed the second
lap in 29.17 seconds. What was her total time for the
two laps? 57.93 seconds
Course 2