Math
Least Common Multiple Calculator
Find the smallest positive number that is a multiple of both of two numbers.
The result is the smallest positive number that both entered numbers divide into exactly.
Formula
Least common multiple = (first number × second number) ÷ their greatest common divisor.
How it works
Enter two whole numbers. The calculator first finds their greatest common divisor, then uses it to work out the smallest number both divide into exactly.
Worked example
For example, for 12 and 18, the greatest common divisor is 6, so the least common multiple is (12 × 18) ÷ 6 = 36.
FAQs
What does the Least Common Multiple do?
It takes the values you enter and works out the least common multiple for you, showing the result straight away.
What should I enter?
Enter ordinary numbers in the boxes above. If a value does not make sense for this calculation, the page will ask you to check it instead of showing a wrong answer.
Can I use the result for homework or everyday math?
Yes. It is a general-purpose math helper; for exam or professional work, still check the steps against your own working.
Related calculators
Arithmetic Sequence Calculator
Instant result, no sign-up.
All tools are free.
Each page shows the formula it uses, so you can check the result yourself.
Built for phone browsers.
Start with a free calculator
Search, pick a calculator, and get an instant result. No sign-up, no download.