In mathematics, Factorial of a number means taking the product of all positive integers less than or equal to the given number. Or the product of multiplying all numbers from one to the given number. For example, the factorial of 6 is 1x2x3x4x5x6=720. Factorial has many uses, specifically in combinatorics or counting problems, as this is a building block for coming up with more complex counting formula. However, this also have uses in other branch of mathematics, hence writing program that is math heavy may need to have a way of computing factorial. If you are working with the Java programming language, this post might help. This post will show example on how to compute factorial in Java. We will help write a factorial program in Java.