Calculyn

LCM and GCF Calculator

Find the greatest common factor and least common multiple of two whole numbers.

Results update as you type.

Greatest common factor

6
Least common multiple
36
Greatest common factor6

Was this calculator helpful?

Quick answer

For 12 and 18, the GCF is 6 and the LCM is 36.

How it works

The GCF is the largest number that divides both numbers evenly. The LCM is the smallest number both divide into. They're linked: LCM = a × b ÷ GCF.

Formula

GCF via Euclid's algorithm · LCM = a × b ÷ GCF

Assumptions & limitations

  • Results are rounded for display.

Frequently asked questions

What's GCF used for?

Simplifying fractions: divide the top and bottom by their GCF.

What's LCM used for?

Finding a common denominator when adding fractions.