Curriculum › Math ›Grade 4

Grade 4 Math · Level 2, Multiplication, Division & Factors

Prime Factorization

How the lesson starts: Prime Factorization

1. Ollie's number trees

   Hoot hoot! Ollie the owl grows number trees. Each branch splits a number into two factors. The tree keeps growing until every leaf is prime. Let's climb up and see!

2. Growing a tree

   Let's grow 24. Split it into 4 × 6. 4 isn't prime, so split it into 2 × 2. 6 isn't prime, so split it into 2 × 3. Now every leaf is prime! Count them: 2, 2, 2, 3. Four prime factors.

3. A shortcut for repeats

   Writing 2 × 2 × 2 is long. There are three 2s, so write 2³. So 24 = 2³ × 3. Check it: 8 × 3 = 24. Remember, 2³ means three 2s multiplied, not 2 × 3!