Fluent addition and subtraction (age 9+) · 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 9-10
Name ______________________   Date ____________

  1. What is 60,000 - 25,000?

    • 85,000
    • 35,000
    • 45,000
    • 30,000

  2. What is 26,839 + 47,586?

    • 74,425
    • 73,425
    • 74,325
    • 64,425

  3. When adding 34,567 + 28,945 in columns, which digits do you add first?

    • 3 and 2, the ten thousands
    • 7 and 5, the ones
    • 4 and 8, the thousands

  4. True or false: if the top digit is smaller than the bottom digit, you borrow from the column to its left.

    Circle one:   True   False

  5. Zoe lines up the digits by place value before adding 52,308 + 7,946. Is that the right start?

    Circle one:   True   False

  6. Adding 8, 7, and 9 in one column gives 24. What do you write below the line, and what do you carry?

    • Write 4, carry 2
    • Write 24, carry 0
    • Write 2, carry 4

  7. What is 700,000 - 381,465?

    • 328,535
    • 419,545
    • 318,535
    • 318,545

  8. What is 100,000 - 45,678?

    Answer: ______________

  9. Leo subtracted 500,000 − 234,178 and got 275,822. Where did he most likely make a mistake?

    • In the ones column, where 10 − 8 should give 2
    • In the hundreds column, where 9 − 1 should give 8
    • In the ten thousands, where he used 10, not 9

  10. Fin says 600,000 - 247,315 needs exchanges because the top number has zeros above bigger digits. Is Fin right?

    Circle one:   True   False

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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_Yw1_4Nfsql-s1

  1. 35,000 · In columns, the ones, tens and hundreds give 0. The thousands need an exchange: 10 - 5 = 5. The ten thousands give 5 - 2 = 3. The answer is 35,000.
  2. 74,425 · Ones 9 + 6 = 15, tens 3 + 8 + 1 = 12, hundreds 8 + 5 + 1 = 14, thousands 6 + 7 + 1 = 14, ten thousands 2 + 4 + 1 = 7. The total is 74,425.
  3. 7 and 5, the ones · You always start at the ones column, the column farthest to the right, then move left one column at a time.
  4. True · Borrowing turns the column with the small digit into a bigger number so you can subtract.
  5. True · Zoe is right: lining up the places means ones add to ones, tens to tens and hundreds to hundreds.
  6. Write 4, carry 2 · 24 has a 4 in the ones place and a 2 in the tens place, so you write 4 and carry 2.
  7. 318,535 · Exchange from the 7 through the zeros: 6, 9, 9, 9, 9, 10. Then 10 - 5 = 5, 9 - 6 = 3, 9 - 4 = 5, 9 - 1 = 8, 9 - 8 = 1 and 6 - 3 = 3. The answer is 318,535.
  8. 54322 · 100,000 - 45,678 = 54,322.
  9. In the ten thousands, where he used 10, not 9 · The correct answer is 265,822. Only the ten thousands digit differs. After the exchange passes through, that column should be 9, and 9 − 3 = 6. Leo used 10 there, and 10 − 3 = 7.
  10. True · Fin is right: zeros up top force exchanges before subtracting.
Worksheet · LightMySky