What does it mean to share a common factor?

Answer 1

A common factor of several numbers is a number that can divide evenly into each one of them.

'10' is a common factor of 20 and 30.

'5' is a common factor of 10 and 15.

'3' is a common factor of 6, 9, and 12.

'2' is a common factor of all even numbers.

'1' is a common factor of all whole numbers.

Answer 2

Usually, you are given two numbers like 30 and 42. Then you are asked to list the factors they share (have in common). That answer is 1, 2, 3 and 6. You might be asked for the largest (greatest) of these. The GCF is 6.

Answer 3

All numbers have factors. Some numbers have some of the same factors as other numbers. These are known as common factors. Since 6 and 9 both have 3 as a factor, they share a common factor.