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6th grade · Math · Unit 1 of 17

Facts & Factors

Facts, primes, GCF and LCM

What your child practices

Quick recall of multiplication and division facts, plus factors, multiples and prime numbers, the greatest common factor (GCF) and least common multiple (LCM), and word problems that use them.

Alaska content standards learning standard: 6.NS.4 · greatest common factor and least common multiple

How we explain it

Children can open this short lesson before they practice.

  1. A factor divides a number evenly. 3 and 4 are factors of 12.
  2. The greatest common factor (GCF) is the biggest factor two numbers share.
  3. The least common multiple (LCM) is the smallest multiple they share.

Example: Find the GCF of 12 and 18. Factors of 12: 1, 2, 3, 4, 6, 12. Factors of 18: 1, 2, 3, 6, 9, 18. The biggest shared one is 6. Answer: 6

Facts & Factors in Alaska

In the Alaska content standards, this is unit 1 of 17 in 6th grade Math, before Mixed Numbers & Ratios.

Gradelings describes a child's practice on this unit as Beginning, Approaching, Meeting or Exceeding (Four practice steps). That reflects practice, not a report-card mark: the teacher decides the mark.

Source: Alaska Department of Education and Early Development

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 of these numbers is prime?

    • 49
    • 27
    • 43
    • 51

  2. Question 2

    What is 21 ÷ 3?

    21 ÷ 3 = ?

    answer box

  3. Question 3

    What is the greatest common factor (GCF) of 28 and 20?

    answer box

  4. Question 4

    Which number is a multiple of 9?

    • 82
    • 84
    • 81
    • 79

  5. Question 5

    What number goes in the box?

    4 × = 28

    • 5
    • 6
    • 7
    • 8

  6. Question 6

    What is 9 × 5?

    9 × 5 = ?

    answer box

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