To find the least common multiple of two numbers, you list each number's multiples (skip-count up) and hunt for the first one they share. That runs on multiplication facts and smooth skip-counting. Warm these up and LCM feels easy.
Answer these 3, then press Show my path. No grade — this just points you to the right level.
1. What is 3 × 4?
2. Skip-count by 5: 5, 10, 15, ___?
3. Which number is a multiple of 4?
A multiple of a number is what you get by skip-counting it: multiples of 3 are 3, 6, 9, 12, 15… A common multiple of two numbers shows up in both lists. The least common multiple (LCM) is the smallest one they share.
Your quick check picks one for you, but you can switch any time:
Level 0 Let's skip-count one step at a time.
A. Skip-count by 2: 2, 4, ___?
4 + 2 = 6.
B. Skip-count by 3: 3, 6, ___?
6 + 3 = 9.
C. Skip-count by 5: 5, 10, ___?
10 + 5 = 15.
Level 1 List multiples, then find a shared one.
A. What is the 4th multiple of 3? (3, 6, 9, ___)
3 × 4 = 12.
B. Which number is a common multiple of 2 and 3?
Multiples of 2: 2,4,6,8. Multiples of 3: 3,6,9. They share 6.
Level 2 Warm-up straight into LCM.
A. What is the LCM of 4 and 6?
4: 4,8,12. 6: 6,12. First shared = 12.
B. What is the LCM of 3 and 5?
3: 3,6,9,12,15. 5: 5,10,15. First shared = 15.
1. Which number is a multiple of 6?
Skip-count by 6: 6, 12, 18, 24. 18 is on the list.
2. What is the least common multiple of 2 and 5?
2: 2,4,6,8,10. 5: 5,10. First shared = 10.
You've practiced exactly what Lesson 1-3 uses. Time to dive in.
Start Lesson 1-3 →