Sum of Digits Program in C#

The Sum of Digits program is a frequently asked question when preparing for internship programmes. In this program, you’re tasked with finding the total of given digits.

To find the solution to this program, you may need knowledge of looping and basic mathematics. You might wonder why mathematics is important, am I correct? Let’s find the answer. If you haven’t checked the patterns and pyramids programs page, do take a look.

Understanding the Sum of Digits Challenge

I believe you’re able to understand the question, am I correct? If not, let me rephrase the question. The problem is to find the total of a given number. In other words, the interviewer provides you with a number, such as 2334, and you have to sum each digit from the given number. Your answer would be 12

Logic behind the Sum of Digits Program

Now, you may wonder that this is easy to find the total, but what if I say it’s not as easy as you think. Can you explain in a comment the logic of how to separate out each digit?

Let’s begin. Your task is to find the total of each digit, which means the first step is to separate out each digit. To tackle this problem, you need to have mathematical skills. If you don’t have them, don’t worry; we’ll solve it together.

Let’s assume the interviewer gives you the number 3422. To separate out each digit, use the modulo (%) sign to get the remainder digit. Then, divide it by 10 to remove that remainder from the main number. To apply this process to all the digits, we need to have a loop to iterate through them. In every iteration, you’ll sum the remainder, and after completing all iterations, you’ll find the answer.

Implementation in Program

Let’s delve into the programming aspect to implement the logic and solve this problem together.

Step 1

The first step is to determine how many variables you need to begin. Your answer would be that you require two variables to start. The first one is an integer input value, provided by the interviewer. The second one is an integer sum, which represents the program’s output. Create these variables and address the problem step by step.

static void Main(string[] args)
{
    int input = 3242;

    int sum = 0;
}

Step 2

The second step is to create a loop to separate out each digit from the given number. Pay close attention as I am going to use a while loop. The condition to close the while loop is that our given number must be greater than 0. This is because, as discussed in the logic explanation, with each iteration, we remove a remainder digit from the given number.

In the while loop, first, we find the remainder of the given number. Then, we add the remainder value to the sum and divide the given number to remove the remainder.

In each iteration, the given number is divided by 10 to remove the remainder value until it becomes 0 or less than it.

 static void Main(string[] args)
 {
     int input = 3242;

     int sum = 0;

     while (input > 0)
     {
         sum += (input % 10);

         input /= 10;
     }

     Console.WriteLine(sum);
 }

Summarizing The Sum of Digits Program

To tackle the problem of finding the sum of digits in a given number, we first initialise two variables: one to hold the input value provided by the interviewer and another to store the sum of the digits. Employing a while loop, we iterate through the given number, extracting each digit by calculating the remainder when divided by 10. This remainder is then added to the sum. We continue this process, updating the given number by dividing it by 10 to remove the last digit, until the number becomes 0 or less. After completing the loop, the sum variable contains the total sum of the digits from the original number.