Introduction

Given a five digit integer, print the sum of its digit
Input: 5 digit number, n
Output: sum of 5 digit number

Input and Output Format

# Input
10564

# Output
16

{: file="Sum Of Digits of a Five Digit Number.c” }

$1+0+5+6+4=16$

This is a watered-down version of the question
{: .prompt-info }

Process

This was my thought process while attempting this challenge.

1. Calculate the number of digits
   1. By dividing the number by 10 and incrementing a counter in a while loop
   2. The number of digits can be found
2. In a for loop to loop through the total number of digits (5)
   1. sum += number % 10
   2. number /= 10
      1. This is to remove the LSB of the number for each iteration of the loop
3. Print out the sum

Code

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26

#include <stdio.h>
#include <string.h>
#include <math.h>
#include <stdlib.h>

int main() {

    int n;
    scanf("%d", &n);
    //Complete the code to calculate the sum of the five digits on n.
    int sum = 0, divisor=10, x = n;
    if (n>=10000 && n <= 99999){
        int noOfDigits = 0;
        while (n!= 0){
            n /= 10;
            noOfDigits++;
        }

        for (int i = 0; i<= noOfDigits; i++){
            sum += x % divisor;
            x /= divisor;
        }
        printf("%d",sum);
    }
    return 0;
}

{: file="Sum Of Digits of a Five Digit Number.c” }

Afterthoughts

I initially thought that I have to increment the mod divisor by 10 everytime (i.e. $10 \times 10 \times 10$) but soon realize that it is only going to make the number bigger.

I use the variable n to calculate the number of digits and used the same variable to calculate the sum, this gave me a result of 0 cuz n started from 0 in the loop!

I then realize I should probably initialize sum to 0 cuz any uninitialized number will be given garbage, this would screw up the sum of numbers.