How to calculate factorial of large number in Java?

Problem Description :

Write a program in Java that calculates factorial of a large number.

Java program that calculates factorial of a large number.

Factorial of large number in Java

Concept :

The factorial of non-negative integer is denoted by n! and it is the product of all positive integers less than or equal to n. For example - 5! = 5 X 4 X 3 X 2 X 1 = 120.

For calculating factorial, we are using BigInteger class that is present in java.math.* package.

Java Program :

package com.javamultiplex.number; import java.math.BigInteger; import java.util.Scanner; /** * * @author Rohit Agarwal * @category Number Problems * @problem How to calculate factorial of large number? * */ public class FactorialOfLargeNumber { public static void main(String[] args) { Scanner input = null; try { input = new Scanner(System.in); System.out.println("Enter number : "); int num = input.nextInt(); BigInteger result = getFactorial(num); System.out.println("Factorial is : " + result); } finally { if (input != null) { input.close(); } } } private static BigInteger getFactorial(int num) { // Converting int to String. String number = String.valueOf(num); // Converting String to BigInteger. BigInteger n = new BigInteger(number); // ZERO=0 BigInteger ZERO = BigInteger.ZERO; // ONE=1 BigInteger ONE = BigInteger.ONE; // fact=1 BigInteger fact = BigInteger.ONE; // while(n!=0) while (!(n.equals(ZERO))) { // fact=fact*n fact = fact.multiply(n); // n=n-1 n = n.subtract(ONE); } return fact; } }

Output :

Output - How to calculate factorial of a very large number in Java?

References :

https://en.wikipedia.org/wiki/Factorial

https://docs.oracle.com/javase/7/docs/api/java/math/BigInteger.html

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Tags : Calculate factorial in Java, Solution in Java, large number, BigInteger, if else statement, while loop, String.

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