# C program to calculate the value of nPr for a given value of n & r

|In this C Programming example, we will implement the program to find the value of **nPr** for a given value of n & r and print the output on the console.

Table of Contents

## 1. What is nPr in Probability – Mathematics?

`nPr`

is a **probability function** that represents *permutations.* `nPr`

represents the probability of selecting an ordered set of ‘**r**’ objects from a group of ‘**n’ **number of objects. The order of objects matters in the** **case of permutation. The formula to calculate nPr is –

nPr(n,r) = n! / (n-r)!Here, n = the total number of items or net size. r = It is the subnet size or total number of items chosen from sample.n!is factorial(n) which is represented as 1*2*....*(n-1)*n Similary the explanation for (n-r)! is also same.

Example:Inputn: 4 r: 3Formula4!/(4-3)! = 24/1 = 24Output4P3 is 24

Helpful topics to understand this program better are-

## 2. C Program to find the value of nPr for a given value of n & r

Let’s discuss the execution(kind of pseudocode) for the program to find the value of nPr for a given value of n & r in C.

- Initially, the program will prompt the user to enter the values of n and r and then pass those values to the
`nPr(n, r)`

function. - In the
`int nPr(int n, int r)`

function, the factorial of the values are calculated using the`int fact(int n)`

function. - After calculating the factorial the output is returned and printed on the console.

In this C Programming example, we have discussed how *to find the value of nPr for a given value of n & r in C*.

#include <stdio.h> int fact(int n) { if (n <= 1) { return 1; } return n * fact(n - 1); } int nPr(int n, int r) { return fact(n) / fact(n - r); } int main() { int n, r; printf("Enter the value of n: "); scanf("%d", &n); printf("Enter the value of r: "); scanf("%d", &r); printf("The value of %dP%d is %d", n, r, nPr(n, r)); return 0; }

**Note:** Only whole positive integer numbers are valid.

OutputEnter the value of n: 5 Enter the value of r: 2 The value of 5P2 is 20

## 3. Conclusion

In this C Programming example, we have discussed how to find the value of nPr for a given value of n & r and discussed the steps of the program in detail.

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