The greatest common factor of two numbers is the largest number that divides into both without a remainder. Finding it by prime factorization is what lets you reduce a fraction to lowest terms in a single step.
Math Dictionary / Greatest Common Factor
Greatest Common Factor
The greatest common factor is the largest factor shared by two or more numbers.
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What it means
It is often used to simplify fractions or factor expressions.
Also called: GCF
Examples
| GCF of 12 and 18 is 6 |
| GCF of 8 and 20 is 4 |
| Use common factors to simplify fractions |
Common mistake
The greatest common factor is a factor, not a multiple.
Try one
Question: What is the GCF of 10 and 15?
Show answer
5.