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Mathematics · Grades 4–7

Greatest common factor

A factor divides a whole number without a remainder.

Make a worksheet

The key idea

A factor divides a whole number without a remainder.

gcd(a,b) = gcd(b, a mod b)

Worked examples

Find the greatest common factor of 123 and 50.

gcd(123, 50) = 1

1

Find the greatest common factor of 101 and 66.

gcd(101, 66) = 1

1

Try it yourself

  1. Find the greatest common factor of 131 and 58.

  2. Find the greatest common factor of 47 and 20.

Check your understanding

Answers and marking notes
  1. 1

    gcd(131, 58) = 1

  2. 1

    gcd(47, 20) = 1

Further reading and review references

These are reference links, not copied exercises, institutional endorsement or proof of independent review.

Learning preview · teacher review required. Grade bands are approximate, not official curriculum alignment.