Addition and subtraction strategies (age 10+) · seed 1 · A4, ink-friendly. The answer key prints on its own page for grown-ups.

Adding and subtracting decimals

Mathematics · Addition & Subtraction · ages 10-11
Name ______________________   Date ____________

  1. What is 2.57 + 3.64?

    • 5.21
    • 6.21
    • 6.11
    • 7.21

  2. Calculate 4.36 + 1.95.

    Answer: ______________

  3. When you add or subtract decimals, what is the first step?

    • Line up the decimal points
    • Add the digits in any order
    • Round both numbers first

  4. In 3.45 + 2.78, which column do you add first?

    • The ones column
    • The tenths column
    • Hundredths

  5. Subtract: 5.03 − 2.67.

    Answer: ______________

  6. Pete says 5.48 + 2.75 = 7.13. Is Pete right?

    Circle one:   True   False

  7. Subtract 7.02 - 4.58 in columns. What is the answer?

    Answer: ______________

  8. Add 3.45 + 2.78. What is the sum?

    Answer: ______________

  9. Priya worked out 5.03 − 2.67 and got 3.64. In each column she took the smaller digit from the bigger one. What mistake did she make?

    • She flipped the digits instead of borrowing
    • She lined up the decimal points wrongly
    • She added the numbers instead of subtracting

  10. Calculate 12.5 - 7.85.

    Answer: ______________

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Answer key

For grown-ups. Fold this page away before handing over the rest.

Adding and subtracting decimals W1-mt_JH_6RpNWjr-s1

  1. 6.21 · Hundredths 7 + 4 = 11, tenths 5 + 6 + 1 = 12, ones 2 + 3 + 1 = 6. The sum is 6.21.
  2. 6.31 · 4.36 + 1.95 = 6.31, with a carry from the hundredths and from the tenths.
  3. Line up the decimal points · Lining up the decimal points lines up matching place values, so each column adds or subtracts correctly.
  4. Hundredths · Just like whole-number addition, start from the smallest place value: hundredths.
  5. 2.36 · Borrow across the 0 tenths: 5.03 becomes 4 ones, 9 tenths, 13 hundredths. 13 − 7 = 6, 9 − 6 = 3, 4 − 2 = 2, giving 2.36.
  6. False · Pete's total is incorrect because he dropped both carries. The correct total is 8.23.
  7. 2.44 · 7.02 has 0 tenths. Trade 1 one for 10 tenths, then 1 tenth for 10 hundredths, making 6 ones, 9 tenths and 12 hundredths. Then 12 - 8 = 4, 9 - 5 = 4 and 6 - 4 = 2, so the answer is 2.44.
  8. 6.23 · Hundredths: 5 + 8 = 13, write 3 carry 1. Tenths: 4 + 7 + 1 = 12, write 2 carry 1. Ones: 3 + 2 + 1 = 6. The sum is 6.23.
  9. She flipped the digits instead of borrowing · 5.03 has 3 hundredths and 0 tenths, so she needed to borrow. Taking 3 from 7 and 0 from 6 flips the columns. The correct answer is 2.36.
  10. 4.65 · Write 12.5 as 12.50. Exchange from the tenths, the ones and the ten: 10 - 5 = 5, 14 - 8 = 6 and 11 - 7 = 4. The answer is 4.65.
Worksheet · LightMySky