1. Number Sense & Operations
Adding and Subtracting Decimals
© 2013 Meredith S. Moody

2. Objective: You will be able to…
Add decimals
Subtract decimals
© 2013 Meredith S. Moody

3. Place value chart Draw your own copy of this place value chart.
© 2013 Meredith S. Moody

4. Practice writing decimals
Using the place value chart to help you, write the following decimals:
One and three hundredths
1.03
Fifteen and eight-hundred seventy-five thousandths
15.875
Nine tenths
0.9
© 2013 Meredith S. Moody

5. Comparing decimals
To compare decimals, you must compare the VALUE of corresponding place values
For example, is greater than because four tenths is greater than zero tenths
© 2013 Meredith S. Moody

6. Guided practice comparing decimals
Compare the following decimals using <, >, or =
2.89 and
3 ones are > 2 ones, so > 2.89
and
9 tenths are greater than 0 tenths, so >14.098
and 0.23
2 tenths = 2 tenths; 3 hundredths = 3 hundredths; zeros are =, so = .23
© 2013 Meredith S. Moody

7. Adding decimals Step 1: Step 2: Step 3: Step 4: Step 5:
Write the number with more digits (longer #) first
Step 2:
Write the other number beneath it; LINE UP THE DECIMALS!!
Step 3:
Add zeros to fill in the spaces on the shorter number
Step 4:
Add the digits
Step 5:
Bring your decimal STRAIGHT DOWN!!!!!!!
© 2013 Meredith S. Moody

8. Guided practice 1, addition 2 . 6 8 1 + 3 5
© 2013 Meredith S. Moody

9. Guided practice 2, addition 1 5 . 2 7 9 + 8
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10. Guided practice 3, addition 2 3 4 . 1 7 8 +
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11. You try: Addition Add the following decimals: 32.07 + 10.1204
16.353
© 2013 Meredith S. Moody

12. Subtracting decimals Step 1: Step 2: Step 3: Step 4: Step 5:
Write the number with the GREATEST VALUE first
Step 2:
Write the other number beneath it; LINE UP THE DECIMALS!!
Step 3:
Add zeros to fill in the spaces on the number with fewer digits
Step 4:
Subtract the digits
Step 5:
Bring down your decimal STRAIGHT DOWN!!!!!!!
© 2013 Meredith S. Moody

13. Guided practice 1, subtraction 3 . 8 5 - 2 6 1 9
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14. Guided practice 2, subtraction 1 5 . 2 7 9 - 8 3 4
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15. Guided practice 3, subtraction 2 3 4 . 1 7 8 - 9 6
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16. You try: Subtraction 32.07 - 10.1204 2.34 - 14.013 21.9496 11.673
© 2013 Meredith S. Moody