Adding and subtracting (age 8+) · seed 1 · A4, ink-friendly. The answer key prints on its own page for grown-ups.

Adding and subtracting big numbers

Mathematics · Addition & Subtraction · ages 8-9
Name ______________________   Date ____________

  1. What is 4000 + 250 + 36?

    Answer: ______________

  2. What is 2345 + 1231?

    • 3566
    • 3476
    • 3576
    • 3676

  3. In columnar addition, a column adds up to 12. What do you write in that column, and what do you carry?

    • Write 2, carry 1
    • Write 1, carry 2
    • Write 12, carry nothing

  4. Estimating your answer can help you check whether it is reasonable.

    Circle one:   True   False

  5. What is 5000 - 1678?

    Answer: ______________

  6. Which is the best estimate to check 3,891 + 2,097?

    • about 5,000
    • about 4,000
    • about 6,000

  7. What is 6000 - 2435?

    • 3565
    • 3665
    • 4565
    • 3465

  8. Lena estimates 4873 + 2105 as 4900 + 2100 = 7000. The exact answer is 6978. She says it is near 7000. Is Lena right?

    Circle one:   True   False

  9. Sam is subtracting 4,006 − 1,738. The ones column needs an exchange, but the tens and hundreds digits are both 0. What should Sam do?

    • Write 0 in the ones place because 6 take away 8 cannot work
    • Exchange from the thousands, passing through each 0
    • Take 6 away from 8 instead, because 8 is the bigger digit

  10. Which addition undoes 756 - 348 = 408?

    • 756 + 408
    • 408 + 348
    • 408 + 756
    • 348 + 348
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Answer key

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

Adding and subtracting big numbers W1-mt_mpS-JK_p_m-s1

  1. 4286 · 4000 + 250 + 36 = 4286.
  2. 3576 · 2345 + 1231 = 3576.
  3. Write 2, carry 1 · The ones digit of 12 is 2, so you write 2 and carry the 1 ten to the next column.
  4. True · Rounding the numbers first gives a quick number to compare your exact answer against.
  5. 3322 · 5000 - 1678 = 3322.
  6. about 6,000 · 3,891 rounds to about 4,000 and 2,097 rounds to about 2,000, so the total should be near 6,000.
  7. 3565 · 6000 - 2435 = 3565 after exchanges across columns.
  8. True · Lena is right: 6978 is close to the estimate 7000.
  9. Exchange from the thousands, passing through each 0 · When a column is 0, the exchange has to come from further left, passing through each 0 column on the way.
  10. 408 + 348 · 408 + 348 = 756 gives back the starting number.
Worksheet · LightMySky