C Exercises: Multiply two integers without using multiplication, division, bitwise operators, and loops

C Programming Mathematics: Exercise-20 with Solution

Write a C program to multiply two integers without using multiplication, division, bitwise operators, and loops.

Example 1:
Input: n1 = 50
Input: n2 = 12
Output: 600
Example 2:
Input: n1 = 0
Input: n2 = 12
Output: 0

Sample Solution:

C Code:

#include <stdio.h>

int multiply_two_nums(int a, int b) { 
          
        /* 0 multiplied with anything gives 0 */
        if (b == 0) 
            return 0; 
      
        if (b > 0) 
            return (a + multiply_two_nums(a, b - 1)); 
            
        if (b < 0) 
            return -multiply_two_nums(a, -b); 
              
        return -1; 
    } 
  
int main(void)
{ 
    int n1 = 50; 
    int n2 = 12;
    printf("\n %d x %d = %d",n1, n2, multiply_two_nums(n1, n2));  
    n1 = 0; 
    n2 = 12;
    printf("\n %d x %d = %d",n1, n2, multiply_two_nums(n1, n2)); 
    return 0;    
}

Sample Output:

50 x 12 = 600
 0 x 12 = 0

Flowchart:

C Programming Code Editor:

Improve this sample solution and post your code through Disqus.

Previous: Write a C program to find the square root of a number using Babylonian method.
Next: Write a C program to calculate and print average (or mean) of the stream of given numbers.