Question

How to sum the digit of a factorial of a number in C

Answer 1

#include <stdio.h>

int sumDigits(long num) {
    int sum = 0;
    while (num != 0) {
        sum += num % 10;
        num /= 10;
    }
      
    return sum;
}
  
long factorial(long n) {
    return (n==1 || n==0) ? 1 : n * factorial(n - 1);
}

int main(void) {
    long number = 20;
  
    long result = factorial(number);

    printf("factorial = %ld\n", result);
    
    printf("sum digits = %d", sumDigits(result));
  
    return 0;
}
 
 
 
 
/*
run:
 
factorial = 2432902008176640000
sum digits = 54
 
*/

 

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