Greatest Common Divisor

The highest common factor (HCF), also called the greatest common divisor, is the largest number that divides exactly into two numbers. In NSW Year 7 maths (NESA outcome MA4‑FRC‑C‑01) it is the quickest way to simplify fractions.

You will find the HCF by listing common factors or by matching shared primes in a Venn diagram or index form, use it to write fractions in simplest form, and solve sharing problems such as packing fruit into identical bags or cutting timber into equal lengths. You will also check that the HCF divides both numbers. It is part of Year 7 Whole Numbers.