Pset1 Credit- How should I proceed to add the sum of multiplied digits & further addition with remaining credit card numbers?

Question

I can pretty much select the digits, multiply the digits by 2 & add the particular digits of the multiplied number. But as of now I can only print them not add them. I also have to add this sum to the remaining numbers in the credit card & then check for modulo 10. How should I do this? Should I change my code(it took me a serious effort to get to this point)?

#include <stdio.h>
#include <cs50.h>

int main(void)

{
    long long n = get_long("n:"); // gets you CC number
    int count = 0;
    int z;
    int k;
    int a;
    int b;
    int c;
    int d;
    
    
    while(n / 10 >= 1) 
    {
        z = n % 10;    
        count++;
        if(count % 2 == 0)  // selects the digit in even places
        {
            k = 2*z;     // multiplies the digit in even places
            a = k % 10;  // gives 1's place of k
            b = k / 10;  // gives 10's place of k
            c = a + b;   // adds the digit
            printf("%i\n", c); // this just exists to check whether the above process is happening
        }
        
        n = n / 10;
        
    }
    
    

    if(n / 10 == 0) // This helps to find the rightmost digit
    {
        z = n % 10;
        count = count + 1;
        if(count % 2 == 0)
        {
            k = 2*z;
            a = k % 10;
            b = k / 10;
            c = a + b;
        }
        
       
     }
    
    

}

Answer 1

You have declared variables to work out the result of your digit math. Why not just declare another variable and add the result to it each time?