Decimal Addition and Subtraction — Answer Key
Part A: Fill in the Blank
Write the missing word or number on each line.
1. 0.5 + 0.25 = 0.75 (rewrite 0.5 as 0.50)
Grade 4 students rewrite 0.5 as 0.50, then add: 0 + 5 = 5 hundredths and 5 + 2 = 7 tenths, giving 0.75.
2. 0.6 - 0.35 = 0.25
Grade 4 learners annex a zero to make 0.60, then subtract 0.35 to get 0.25.
3. 0.4 + 0.18 = 0.58
Grade 4 students rewrite 0.4 as 0.40, add hundredths to get 8, and tenths to get 5, giving 0.58.
4. Write the fraction 3/10 as a decimal: 0.3
Grade 4 learners know 3/10 means 3 tenths, written as 0.3.
5. Write the fraction 27/100 as a decimal: 0.27
Grade 4 students write 27/100 as 0.27 because the digits 2 and 7 occupy the tenths and hundredths places.
6. 0.7 = 0.70 (annex one zero)
Grade 4 learners annex a zero so 0.7 becomes 0.70, an equivalent decimal useful for adding hundredths.
7. 0.9 - 0.45 = 0.45
Grade 4 students rewrite 0.9 as 0.90, then subtract 0.45 to get 0.45.
8. 0.32 + 0.4 = 0.72
Grade 4 learners annex a zero to 0.4, then add columns to get 0.72.
9. Write 0.8 as a fraction with denominator 10: 8/10
Grade 4 students recognize 0.8 as 8 tenths, equivalent to the fraction 8/10.
Part B: Matching
Match each item on the left to the correct answer on the right.
1. Match each item to its correct answer.
0.3 + 0.4
→ 0.7
0.7
0.5 + 0.25
→ 0.75
0.75
0.9 - 0.4
→ 0.5
0.5
0.6 - 0.35
→ 0.25
0.25
Grade 4 students match each expression to its sum or difference by carefully aligning decimal points and using place value.