Factorial of a Number Full Explanation With Examples

Data Structure / By Rakesh Saini / December 22, 2023

Factorial of a number in computer science and mathematics, the factorial of a non-negative integer n, denoted as n!, is the product of all positive integers less than or equal to n. It is defined as follows:

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Here’s an explanation of how to calculate the factorial of a number using examples in Java, PHP, Dart, and JavaScript:

Factorial Examples of a Number

Below are some examples in different-different languages.

Java Example:


public class FactorialExample {
    public static int factorial(int n) {
        if (n == 0 || n == 1) {
            return 1;
        } else {
            return n * factorial(n - 1);
        }
    }

    public static void main(String[] args) {
        int number = 5; // Change this to the desired number
        int result = factorial(number);
        System.out.println("Factorial of " + number + " is: " + result);
    }
}

PHP Example:


<?php
function factorial($n) {
    if ($n == 0 || $n == 1) {
        return 1;
    } else {
        return $n * factorial($n - 1);
    }
}

$number = 5; // Change this to the desired number
$result = factorial($number);
echo "Factorial of $number is: $result";
?>

Dart Example:


int factorial(int n) {
  if (n == 0 || n == 1) {
    return 1;
  } else {
    return n * factorial(n - 1);
  }
}

void main() {
  int number = 5; // Change this to the desired number
  int result = factorial(number);
  print("Factorial of $number is: $result");
}

JavaScript Example:


function factorial(n) {
    if (n === 0 || n === 1) {
        return 1;
    } else {
        return n * factorial(n - 1);
    }
}

const number = 5; // Change this to the desired number
const result = factorial(number);
console.log(`Factorial of ${number} is: ${result}`);

Replace the number variable with the desired integer for which you want to calculate the factorial. Since it defines the rationale for factorial computation, the recursive function factorial is used in all of the instances..