In C programming, it is often necessary to find the sum of the digits of a given number. In this program, we will write a C program that prompts the user to enter a number, calculates the sum of its digits, and prints the result.

**Problem Statement**

The problem statement is to write a C program that prompts the user to enter a number, calculates the sum of its digits, and prints the result.

**Solution**

Here is the C program to find the sum of digits of a number:

#include <stdio.h> int main() { int num, sum = 0, remainder; printf("Enter an integer: "); scanf("%d", &num); while(num > 0) { remainder = num % 10; sum += remainder; num /= 10; } printf("The sum of digits is %d\n", sum); return 0; }

**Output**

**Explanation**

First, we include the `stdio.h`

header file which is used for input and output functions. Then, we define the `main()`

function as the starting point of our program.

We declare three integer variables – `num`

, `sum`

, and `remainder`

. `num`

is used to store the number entered by the user, `sum`

is used to store the sum of the digits, and `remainder`

is used to store the remainder obtained after dividing `num`

by 10.

Next, we prompt the user to enter a number using the `printf()`

function. The `scanf()`

function is used to read in the number entered by the user. The format specifier `%d`

is used to specify that the input should be read as an integer.

We then use a `while`

loop to calculate the sum of the digits. In each iteration of the loop, we calculate the remainder of `num`

divided by 10 using the modulo operator `%`

. We add the remainder to the `sum`

variable, and then divide `num`

by 10 to remove the last digit from `num`

. We repeat this process until `num`

becomes 0.

Finally, we print the result using the `printf()`

function. We use the format specifier `%d`

to print the original number entered by the user, and `%d`

again to print the sum of its digits.

**Conclusion**

In this tutorial, we learned how to write a C program to find the sum of digits of a number. We used a `while`

loop to iterate through the digits of the number, and calculated the sum using the modulo operator `%`

and division operator `/`

. We also used the `printf()`

function to print the result to the console.

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