LCM calculator
Calculator
The calculator needs JavaScript. The tables below give the same numbers for common cases.
How it is worked out
- LCM(a, b) = a × b ÷ GCF(a, b), applied to the numbers one after another.
- Result: 180. Each number divides it exactly: 180 ÷ 12 = 15; 180 ÷ 18 = 10; 180 ÷ 30 = 6.
| Inputs | Answer |
|---|---|
| Whole numbers: 12, 18, 30 | The LCM of 12, 18, 30 is 180. |
| Whole numbers: 4, 6 | The LCM of 4, 6 is 12. |
| Whole numbers: 8, 9, 21 | The LCM of 8, 9, 21 is 504. |
How to use it
The least common multiple (LCM) is the smallest positive number that every one of the numbers divides into exactly. It is found from the GCF: LCM(a, b) = a × b ÷ GCF(a, b), applied to the numbers one after another.
The LCM is the common denominator you use to add fractions, and the time two repeating events next line up.
Frequently asked questions
What is the LCM of 12 and 18?
36.
How do I find the LCM of three numbers?
Find the LCM of the first two, then the LCM of that result and the third.
How are LCM and GCF related?
For two numbers, LCM × GCF equals the product of the numbers.
Method: standard arithmetic shown step by step; no outside data is used. Checked 2026-11-12.
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General information only. Results are plain arithmetic on the numbers you enter; check anything important (money, health, school work) against your own records or the official source.