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Number system · Beginner

LCM — Least Common Multiple

Learn what LCM means, compare three reliable methods, and use the interactive calculator to understand every step.

Try the calculator ↓Start the lesson
LCM(12, 18)= 36The smallest number divisible by both
01

What is LCM?

The Least Common Multiple of two or more numbers is the smallest positive number that is exactly divisible by every one of them.

In simple words

List the multiples of each number. The first number that appears in every list is their LCM.

Example: LCM of 4 and 6

Multiples of 4: 4, 8, 12, 16, 20…

Multiples of 6: 6, 12, 18, 24…

So, the first common multiple is 12.

02

Interactive LCM calculator

Enter two or more whole numbers. You’ll get the answer and a teaching-friendly prime factorisation method.

Use 2–8 positive whole numbers, each no larger than 1,000,000.
LEAST COMMON MULTIPLE36

Prime factorisation method

  1. 12 = 2² × 3
  2. 18 = 2 × 3²
  3. Take the highest power of each prime: 2² × 3²
  4. Multiply them: 4 × 9 = 36
03

Quick LCM insight

⚡

When one number divides the other

If the larger number is already divisible by the smaller number, the larger number is the LCM.

LCM(6, 24) = 24

04

Check your understanding

Find the LCM of 8 and 12.