What is the greatest common factor of 25?

Answer 1

There is neither a greatest common factor nor common factors of a single number, such as 25, because there cannot be any form of common factor without two or more numbers to compare. Common factors are factors that the numbers being compared have in common. The greatest common factor is the largest factor that all the numbers being compared have in common. Thus, since there are not two or more numbers to compare, there are neither common factors nor a greatest common factor.

The factors of 25 are 1, 5, and 25.

The prime factors of 25 are 5 and 5.

Examples:

The common factors of 13 and 25 are only 1; the greatest common factor is 1.

The common factors of 23 and 25 are only 1; the greatest common factor is 1.

The common factors of 25 and 30 are 1 and 5; the greatest common factor is 5.

The common factors of 25 and 42 are only 1; the greatest common factor is 1.

The common factors of 25 and 50 are 1, 5, and 25; the greatest common factor is 25.

Answer 2

For common factors you need more than one number.