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LCM and GCF Calculator

Find the least common multiple (LCM) and greatest common factor (GCF, GCD or HCF) of two or more numbers, with each number's prime factorization. Free.

Separate numbers with commas or spaces.

Greatest common factor (GCF / GCD / HCF)
6
Least common multiple (LCM)
180
12 =
2² × 3
18 =
2 × 3²
30 =
2 × 3 × 5

Common factors and multiples

The greatest common factor (also called the greatest common divisor or highest common factor) is the largest number that divides all your numbers exactly. The least common multiple is the smallest number they all divide into. You'll use the GCF to simplify fractions and the LCM to add fractions with different denominators or to work out when repeating events line up. Enter two or more whole numbers to see both, with each number's prime factorization.

How to use it

  1. 1

    Enter the numbers

    Two or more whole numbers, separated by commas or spaces.

  2. 2

    Read the GCF and LCM

    Both update as you type.

  3. 3

    Check the prime factors

    Each number's prime factorization shows how they're built.

Frequently asked questions

What is the GCF of 12, 18 and 30?

6. The prime factorizations are 2² × 3, 2 × 3² and 2 × 3 × 5, and the factors they share are 2 × 3.

What is the LCM of 4 and 6?

12, the smallest number both divide into.

How are GCF and LCM related?

For two numbers, GCF × LCM = the product of the numbers. For 4 and 6: 2 × 12 = 24 = 4 × 6.

Is anything sent to a server?

No. Everything is calculated in your browser, and nothing you type is stored or sent anywhere.

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