6 — Greatest Common Factor

Greatest Common Factor

Solution & Explanation · ID: C0FECF1D

Question

Find the GCF of 20 and 30.

Hint

Try using either the listing method or prime factorization method.

Concept

The Greatest Common Factor (GCF) is the largest number that divides evenly into all given numbers. We can find it by listing factors or using prime factorization.

Show Answer

10

Show Solution
1

List all factors of 20: 1, 2, 4, 5, 10, 20

2

List all factors of 30: 1, 2, 3, 5, 6, 10, 15, 30

3

Find common factors: 1, 2, 5, 10

4

The greatest common factor is 10

Two columns showing factors. Left column labeled '20:' lists 1, 2, 4, 5, 10, 20. Right column labeled '30:' lists 1, 2, 3, 5, 6, 10, 15, 30. Common factors 1, 2, 5, and 10 are circled in both columns. The number 10 is highlighted as the GCF.