Recursion in C

Find the output of the following recursive algorithm.

 #include<stdio.h>

  int counter = 0;

  int calc(int a, int b) {

  int c;

  counter++;

  if (b==3) {

  return (a*a*a);

          }

  else {

    c = calc(a, b/3);

    return (c*c*c);

 }

}

int main (){

  calc(4, 81);

  printf ("%d", counter);

  }

Output: 4

 Finding factorial of a number by recursion

#include<stdio.h>

long int multiplyNumbers(int n);

int main() {

    int n;

    printf("Enter a positive integer: ");

    scanf("%d",&n);

    printf("Factorial of %d = %ld", n, multiplyNumbers(n));

    return 0;

}

long int multiplyNumbers(int n) {

    if (n>=1)

        return n*multiplyNumbers(n-1);

    else

        return 1;

}

Addition of 10 consecutive numbers using recursion

#include<stdio.h>

int sum(int k);

int main() {

  int result = sum(10);

  printf("%d", result);

  return 0;

}

int sum(int k) {

  if (k > 0) {

    return k + sum(k - 1);

  } else {

    return 0;

  }

}