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🔗 GCD & LCM Calculator
Find the greatest common divisor (GCD/HCF) and least common multiple (LCM) of two numbers.
About this GCD & LCM Calculator
This calculator finds the GCD (also called HCF) and LCM of two whole numbers using the Euclidean algorithm. The GCD is what you need to reduce fractions to their simplest form, and the LCM is what you need to add fractions with different denominators or to find when repeating events line up again.
How to use it
- Enter the two whole numbers.
- Click Calculate GCD & LCM.
- Read the GCD and LCM, with a built-in multiplication check.
Example
For 48 and 180, the GCD is 12 and the LCM is 720 — and 48 × 180 = 8,640 = 12 × 720.
Frequently asked questions
What is the GCD used for?
Simplifying fractions: divide the top and bottom of 48/180 by their GCD 12 and you get 4/15.
What is the LCM used for?
Finding a common denominator, and scheduling: buses every 12 and 18 minutes leave together every 36 minutes — the LCM.
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