7th grade · Math · Unit 2 of 17
Decimal Operations
Add, subtract, multiply, divide decimals
What your child practices
All four operations with decimals, estimating to check answers, ordering decimals, and money problems such as unit prices.
California Content Standards learning standard: 7.NS.2; 7.EE.3 · computing with decimals and solving multi-step problems with rational numbers
How we explain it
Children can open this short lesson before they practice.
- To add or subtract, line up the decimal points.
- Fill empty places with zeros so the numbers match.
- Then add or subtract like whole numbers.
Example: 3.45 + 2.8 = ? Write 2.8 as 2.80 and line up the points. 3.45 + 2.80 = 6.25. Answer: 6.25
Sample questions
A taste of this unit. In the app, questions change every time and get easier or harder to match your child.
Question 1
Which is the best estimate for 59.8 × 9.2?
- 54
- 5400
- 69
- 540
540
Hint: Round each number to a friendly one: 59.8 ≈ 60 and 9.2 ≈ 9. Then 60 × 9 = 540.
Question 2
What is 4 ÷ 0.5?
4 ÷ 0.5 = ?
answer box
8
Hint: Multiply both numbers by 10 so you divide by a whole number: 40 ÷ 5 = 8.
Question 3
What is 6.8 × 0.9?
6.8 × 0.9 = ?
- 61.2
- 0.0612
- 0.612
- 6.12
6.12
Hint: Multiply as if there were no decimal points: 68 × 9 = 612. The factors have 2 decimal places in total, so the product does too: 6.12.
Question 4
What is 23.27 + 8.2?
23.27 + 8.2 = ?
answer box
31.47
Hint: Line up the decimal points and give every number two decimal places: 23.27 + 8.20. Add column by column: 31.47.
Question 5
Use the order of operations: what is 2.9 + 2.5 × 3?
2.9 + 2.5 × 3
- 16.2
- 11.2
- 10.5
- 10.4
10.4
Hint: Multiply before adding: 2.5 × 3 = 7.5. Then 2.9 + 7.5 = 10.4.
Question 6
Put these decimals in order from least to greatest.
- 0.04
- 0.094
- 0.94
- 0.492
- 0.49
0.04 → 0.094 → 0.49 → 0.492 → 0.94
Hint: Compare tenths first, then hundredths, then thousandths. Writing them with the same number of places helps: 0.040, 0.094, 0.490, 0.492, 0.940.