Positive integers are the numbers used when counting. Every positive integer has 1 and itself as factors. This is because 1 times any number gives that number as a result. More factors are found by dividing the number by 2 and then 3, working through the integers in succession. Whenever the answer to the division problem is a positive integer, the two numbers are factors of the original number. For example, when 78 is divided by 6 the answer is 13, so 6 and 13 are factors of 78. On the other hand, 78 divided by 8 equals 9.75. That is not a positive integer, so 8 is not a factor of 78. When working with large numbers, a calculator makes the process go quicker.

The prime factorization of a number is a list of all of its prime factors in multiplication form. Prime numbers have no other factors besides 1 and themselves. The prime factorization of 78 is 2 x 3 x 13. Every positive integer that is not a prime number has one unique prime factorization.