LCM and GCD

Lowest common multiple and greatest common divisor

Enter two or more numbers and the tool works out their lowest common multiple (LCM) and greatest common divisor (GCD) straight away. Useful at school for adding fractions, cancelling them down or divisibility problems, and in practice when you need to know after how many days two events fall together.

What each value means

The greatest common divisor is the largest number that divides all of your numbers without a remainder. It is mostly used for cancelling fractions down. The lowest common multiple is the opposite: the smallest number divisible by all of them, which is what you need when putting fractions over a common denominator. The tool uses Euclid's algorithm, so even large numbers answer instantly.

Frequently asked questions

How many numbers can I enter?

More than two is fine. The LCM and GCD are computed step by step across all of them, so the result holds for the whole group.

What should separate the numbers?

A comma, a space or anything that is not a digit. The tool pulls every positive whole number out of the text by itself.

What if the GCD is one?

That means the numbers share no divisor other than one: they are coprime. Their LCM is then simply their product.