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