Number

HCF (Highest Common Factor)

The largest number that divides exactly into two or more numbers.

Definition

Find by listing factors of each number, or by prime factorisation: take all primes common to both, with the lowest power. The HCF of 18 and 24 is 6.

Example

HCF of 12 and 18: factors of 12 are 1,2,3,4,6,12; factors of 18 are 1,2,3,6,9,18. Common factors: 1,2,3,6. HCF = 6.

Used in these topics

Related terms

LCM (Lowest Common Multiple)

The smallest positive number that is a multiple of two or more numbers.

Factor

A number that divides another exactly, with no remainder.

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