Factors are the numbers that are multiplied together to get another number. To find the factors of a given number, the number is divided by other numbers smaller than the given number, as the factor of any number cannot be greater than the number itself.
For instance, to find the factors of 28, it is divided by numbers less than 28. Since 28 is an even number, 2 is a factor of 28. Similarly, 4, 7 and 14 also divide 28 exactly and do not leave a remainder, thus, the factors of 28 are 1, 2, 4, 7, 14 and 28. The numbers 2 and 7 are also prime numbers, so the prime factors of 28 are the numbers 2 and 7 only. Prime factors do not include any products of the factors, 4 and 14 in this example. The number 1 is not a prime number, and 2 is the only even prime number.
If the number that has to be factored is an even number, division should be started with 2. If the given number is odd, then 2 is not a factor and the smaller odd numbers such as 3, 5 or 7 should be tried.
The smallest factor of any number is always the number 1, and the largest factor of any given number is the number itself.