# C program to find the value of nCr for a given value of n & r

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

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

** nCr** is a

**probability function**that represents

*combination*, it states the selection of ‘

**r**‘ elements from a group or set of ‘

**n**‘ elements, such that the order of elements does not matter. The formula to find combinations of elements is-

Here, n = the total number of items or net size. r = It is the subnet size or total number of items chosen from sample.nCr= n!/(r! * (n-r)!)

Example:Inputn: 8 r: 4Formula8!/(4! * (8−4)!) = 8!/(4! * 4!) = 40320/(24*24) = 70Output4 C 3 is 70

Helpful topics to understand this program better are-

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

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

- Initially, the program will prompt the user to enter the values of
**n**and**r**. - Now, we invoke the function
`int nCr(int n, int r)`

, within this function, we call`int fact(int n)`

function to calculate the required factorial values. - Factorial values are used to calculate the
`nCr`

value and then we print this value on the console.

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

#include <stdio.h> int fact(int n); int nCr(int n, int r) { return fact(n) / (fact(r) * fact(n - r)); } // This functions returns factorial of n int fact(int n) { int res = 1; for (int i = 2; i <= n; i++) { res = res * i; } return res; } 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 %dC%d is %d", n, r, nCr(n, r)); return 0; }

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

OutputEnter the value of n: 5 Enter the value of r: 4 The value of 5C4 is 5

## 3. Conclusion

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

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