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LCM & GCF Calculator Guide
Find the greatest common factor (GCF) and least common multiple (LCM) of two or more whole numbers. These are core tools for simplifying fractions and solving number problems.
GCF is the largest number that divides all your numbers evenly. LCM is the smallest number that all your numbers divide into evenly.
How Do I Find the GCF and LCM?
The GCF is found by taking the common prime factors; the LCM uses each prime factor the greatest number of times it appears. For 12 and 18, the GCF is 6 and the LCM is 36.
Where These Are Used
The GCF simplifies fractions — dividing the numerator and denominator by their GCF reduces the fraction. The LCM finds a common denominator when adding or subtracting fractions with different denominators.
Related: Fraction Calculator, Ratio Calculator, and Average Calculator.
Frequently Asked Questions
What is the GCF?
The greatest common factor is the largest whole number that divides evenly into all the numbers given.
What is the LCM?
The least common multiple is the smallest number that every one of your numbers divides into without a remainder.
How are GCF and LCM related?
For two numbers, the GCF times the LCM equals the product of the two numbers.
What are they used for?
The GCF simplifies fractions, and the LCM gives a common denominator for adding or subtracting fractions.
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