Mental multiplication and division (age 9+) · seed 1 · A4, ink-friendly. The answer key prints on its own page for grown-ups.

Big multiplications and divisions, done in your head

Mathematics · Multiplication & Division · ages 9-10
Name ______________________   Date ____________

  1. Which two facts help you work out 9 × 15 mentally?

    • 9 × 10 and 9 × 5
    • 9 × 20 and 9 × 5
    • 9 × 10 and 9 × 6
    • 9 × 1 and 9 × 5

  2. What is 40 × 60?

    Answer: ______________

  3. What is 30 × 70? Use 3 × 7 = 21 to help.

    • 210
    • 2100
    • 21000

  4. To work out 360 ÷ 9, you can first find 36 ÷ 9 and then put the zero back on the answer.

    Circle one:   True   False

  5. What is 480 ÷ 8? Use 48 ÷ 8 = 6 to help.

    • 6
    • 60
    • 600

  6. Find 6 × 15 by splitting 15 into 10 and 5.

    Answer: ______________

  7. Use 7 × 10 and 7 × 5 to find 7 × 15.

    Answer: ______________

  8. Which is the fastest way to find 50 × 40 in your head?

    • Multiply 5 × 4, then add two zeros
    • Multiply 50 by 4 one digit at a time with no shortcuts
    • Add 50 and 40 together
    • Multiply 5 × 40 without using the zero trick

  9. Ben says 20 × 30 = 6, because 2 × 3 = 6. What went wrong?

    • He forgot to add the two zeros back on
    • He multiplied wrong: 2 × 3 is not 6
    • Nothing, 6 is correct

  10. Which is the quickest way to work out 630 ÷ 7 in your head?

    • Find 6 ÷ 7 first
    • Find 630 ÷ 70
    • Find 63 ÷ 7, then put the zero back on the answer
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Answer key

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

Big multiplications and divisions, done in your head W1-mt_8A3pZNOp7Z-s1

  1. 9 × 10 and 9 × 5 · 15 splits neatly into 10 and 5, so 9 × 10 = 90 and 9 × 5 = 45, which add up to 135.
  2. 2400 · 40 × 60 is the same as 4 × 6 with two zeros tacked on the end, so the answer is 2400.
  3. 2100 · 3 × 7 = 21, then add both zeros from 30 and 70 back on: 2,100.
  4. True · Dropping the zero turns 360 into 36. Once you divide, the zero goes back on: 40.
  5. 60 · 48 ÷ 8 = 6, then put the dropped zero back on: 60.
  6. 90 · 6 × 10 = 60 and 6 × 5 = 30, and 60 + 30 = 90.
  7. 105 · Splitting 15 into 10 and 5 turns a hard fact into two easy ones that add up to 105.
  8. Multiply 5 × 4, then add two zeros · 5 × 4 = 20, and adding back the two zeros from 50 and 40 gives 2000.
  9. He forgot to add the two zeros back on · 2 × 3 = 6 is right, but Ben dropped both zeros. 20 × 30 = 600.
  10. Find 63 ÷ 7, then put the zero back on the answer · Drop the zero to get 63 ÷ 7 = 9, then put it back on: 90.
Worksheet · LightMySky