# Factorial Program in Java using Recursion

Factorials are used in mathematics to calculate permutations and combinations. It is denoted by the exclamatory symbol (!). Suppose, p is a number whose factorial is to be calculated is represented by ** p!.**It is pronounced as

*p factorial*. In this section, we will create a

**Java program to calculate the factorial of a number using iterative and recursive approach.**

Factorial of any number is the multiplication of numbers from that particular number to 1 either in increasing or in decreasing order. In general terms, we can represent the factorial of a number as follows:

p! = p × (p-1) × (p-2) × … × 1 <em>or </em>1 × … × (p-2) × (p-1) × p

For example:

3! = 3 × 2 × 1 *or* 1 × 2 × 3 = 6

4! = 4 × 3 × 2 × 1 *or *1 × 2 × 3 × 4 = 24

**Note:** As per standard mathematical definition, the factorial of any negative number cannot be found. Also, *0!* is always *1.*

Let’s write a Java program that calculates the factorial of a number using Java for loop.