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Grade 6 · Math · Unit 4 of 18

Factors & Primes

Divisibility and prime factors

What your child practises

Using divisibility rules for 2, 3, 4, 5, 6, 8, 9 and 10, telling prime from composite, and writing a number as a product of prime factors.

Prince Edward Island Curriculum curriculum outcome: N3 · divisibility rules, prime numbers and prime factorization

How we explain it

Children can open this short lesson before they practise.

  1. A prime number has exactly two factors: 1 and itself.
  2. A factor tree splits a number into primes.
  3. Divisibility rules help: even numbers divide by 2, and digits that add to a multiple of 3 divide by 3.

Example: Write 12 as a product of prime factors. 12 = 2 × 6. 6 = 2 × 3. So 12 = 2 × 2 × 3. Answer: 2 × 2 × 3

Sample questions

A taste of this unit. In the app, questions change every time and get easier or harder to match your child.

  1. Question 1

    Which number is divisible by 8?

    • 185
    • 97
    • 880

  2. Question 2

    Which shows 45 as a product of prime factors?

    • 3 × 3 × 5
    • 9 × 5
    • 3 × 3 × 2

  3. Question 3

    A number is divisible by 9 when…

    • its digits are all odd
    • the sum of its digits is divisible by 9
    • its last digit is 9

  4. Question 4

    Is 871 divisible by 3?

    • Yes
    • No

  5. Question 5

    Which shows 63 as a product of prime factors?

    • 3 × 3 × 2
    • 3 × 3 × 7
    • 9 × 7

  6. Question 6

    Which number is divisible by 4?

    • 470
    • 759
    • 184

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