Factors, multiples, and primes · seed 1 · A4, ink-friendly. The answer key prints on its own page for grown-ups.

Factors, multiples, and primes

Mathematics · Multiplication & Division · ages 9-11
Name ______________________   Date ____________

  1. What is the 5th multiple of 9?

    Answer: ______________

  2. Which pair of numbers is a factor pair of 24?

    • 3 and 7
    • 4 and 6
    • 5 and 5
    • 2 and 9

  3. Which pair of numbers is a factor pair of 36?

    • (4, 9)
    • (5, 7)
    • (8, 5)

  4. True or false: 9 is a prime number.

    Circle one:   True   False

  5. Which list shows ALL the common factors of 18 and 30?

    • 1, 2, 3, 6
    • 1, 2, 3
    • 1, 3, 6, 9
    • 1, 2, 3, 6, 9

  6. What are the first three common multiples of 6 and 8?

    • 6, 8, 14
    • 24, 48, 72
    • 12, 24, 36

  7. Which number is a common factor of 20 and 30?

    • 4
    • 5
    • 6
    • 8

  8. Which list shows ALL the factor pairs of 28?

    • 1 x 28, 2 x 14, 4 x 7
    • 1 x 28, 2 x 14, 4 x 8
    • 2 x 14, 4 x 7, 5 x 5
    • 1 x 28, 4 x 7, 6 x 6

  9. Two bells ring every 5 and 7 seconds. They just rang together. In how many seconds will they ring together again?

    • 12 seconds
    • 35 seconds
    • 70 seconds
    • 57 seconds

  10. Priya lists the factor pairs of 36 as (1,36), (2,18), (3,12), (4,9), (5,7). What went wrong?

    • She wrote the pairs in the wrong order
    • Nothing is wrong
    • 5 x 7 is not 36, and she also missed the pair (6, 6)
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Answer key

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

Factors, multiples, and primes W1-mt_FHIAv6dfhU-s1

  1. 45 · The multiples of 9 run 9, 18, 27, 36, 45.
  2. 4 and 6 · Four times six is twenty-four, so (4, 6) is a factor pair of 24.
  3. (4, 9) · 4 x 9 = 36. Check the others: 5 x 7 = 35 and 8 x 5 = 40, neither makes 36.
  4. False · 9 has more than one factor pair: (1,9) and (3,3), so it is not prime.
  5. 1, 2, 3, 6 · The shared factors of 18 and 30 are exactly 1, 2, 3, 6.
  6. 24, 48, 72 · Multiples of 6: 6,12,18,24,30,36,42,48... Multiples of 8: 8,16,24,32,40,48... The first three numbers on both lists are 24, 48, 72.
  7. 5 · Five divides both 20 and 30, so 5 is a common factor.
  8. 1 x 28, 2 x 14, 4 x 7 · 28 = 1x28 = 2x14 = 4x7: three pairs in total.
  9. 35 seconds · The ring cycles meet at common multiples of 5 and 7: 35 comes first.
  10. 5 x 7 is not 36, and she also missed the pair (6, 6) · 5 x 7 = 35, not 36, so that pair does not belong. She also stopped before reaching (6, 6), where the numbers meet.
Worksheet · LightMySky