Calculating the factors of 25 is straightforward as they are 1, 5 and 25. The first two factors to be ascertained, sometimes the only two factors, are the number itself and 1. Also, any number that can be divided by itself becomes a factor.
A factor is a number that can evenly be divided into another number. Any number can be divided by itself and one, so those two numbers are always factors. Numbers that can only be divided by 1 and themselves are called prime numbers. When two numbers have no prime factors in common, its greatest common factor is 1. Some numbers have several factors, and some numbers have just the number and 1.