To break a number into its prime factors, you keep splitting it into smaller multiplications until every piece is prime. That runs on quick multiplication facts, knowing which numbers divide evenly, and spotting prime numbers. Warm these up and prime factorization clicks.
Answer these 3, then press Show my path. No grade — this just points you to the right level.
1. What is 4 × 6?
2. Which number divides 20 evenly (no remainder)?
3. Which number is prime (only factors are 1 and itself)?
A prime number has exactly two factors: 1 and itself (like 2, 3, 5, 7). A composite number can be split into smaller factors. Prime factorization means writing a number as a product of only primes.
Your quick check picks one for you, but you can switch any time:
Level 0 Let's split numbers one step at a time.
A. Fill the missing partner: 2 × ___ = 10
What times 2 gives 10? 2 × 5 = 10.
B. Fill the missing partner: 3 × ___ = 9
3 × 3 = 9.
C. 6 splits into 2 × ___?
2 × 3 = 6.
Level 1 Find factor pairs and spot the primes.
A. 8 splits into 2 × ___?
2 × 4 = 8.
B. Which number is prime?
5 has only factors 1 and 5. The others split into smaller numbers.
C. 15 splits into 3 × ___?
3 × 5 = 15.
Level 2 Warm-up straight into prime factorization.
A. 12 = 2 × 2 × ___. Fill the blank.
2 × 2 = 4, and 4 × 3 = 12, so the missing prime is 3.
B. 18 = 2 × 3 × ___. Fill the blank.
2 × 3 = 6, and 6 × 3 = 18, so the missing prime is 3.
1. Which list shows the prime factorization of 8?
Keep splitting until all pieces are prime: 8 = 2 × 4 = 2 × 2 × 2.
2. 20 = 2 × 2 × ___. Fill the blank.
2 × 2 = 4, and 4 × 5 = 20, so the missing prime is 5.
You've practiced exactly what Lesson 1-1 uses. Time to dive in.
Start Lesson 1-1 →