Question

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

Answer 1

#include <iostream>

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 = 9;
   
    long result = factorial(number);
 
    std::cout << "factorial = " << result << "\n";
     
    std::cout << "sum digits = " << sumDigits(result);
}

  
  
/*
run:
  
factorial = 362880
sum digits = 27
  
*/

 

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