# Program To Find nCr & nPr

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In this article, we will learn how to find nCr and nPr using Java program.

### What is Permutation?

Permutation is the process of arranging of all the members in any set into a particular order or sequence.

ex., set A with members 1 & 2 can be arranged into 2 ways such as {1,2,} and {2,1}.

### What is Combination?

Combination is the process of selecting members from any particular set.

ex, if we had to select 2 members at random from set A with members 1, 2 & 3, we would have 3 possibilities namely {1,2}, {2,3} and {1,3}.

### Java Program to Find nCr and nPr

import java.util.Scanner; class NcrAndNpr { double combination(int n,int r) { double com=fact(n)/(fact(n-r)*fact(r)); return com; } // double permutation(int n,int r ) { double per=fact(n)/fact(n-r); return per; } // fact method is used to calculate factorial of number double fact(double n) { int i=1; double fact=1; while(i<=n) { fact=fact*i; i++; } return fact; } public static void main(String arg[]) { NcrAndNpr p=new NcrAndNpr(); Scanner sc=new Scanner(System.in); System.out.println("enter value of n"); int n=sc.nextInt(); System.out.println("enter value of r"); int r=sc.nextInt(); if(n>=r) { // p.permutation(n,r) calls the permutation method which internally calls the fact method and prints the permutation. System.out.println("The value of "+n+"p"+r+" is : "+p.permutation(n,r)); // p.combination(n,r) calls the combination method which internally calls the fact method and prints the combination. System.out.println("The value of "+n+"c"+r+" is : "+p.combination(n,r)); } else System.out.println("n value should be greater than or equals to r value"); } }

#### Output:

enter value of n
12
enter value of r
6
The value of 12p6 is : 665280.0
The value of 12c6 is : 924.0