C PROGRAMMING PROGRAM • OPERATORS & CONVERSIONS

Find the Sum of Digits of a Three-Digit Number

Learn how to find the sum of digits of a three-digit number using a clear C program.

BeginnerDivisionModulusDigit extraction

PROBLEM UNDERSTANDING

Input and expected output

Sample input

Sample output

Digit sum = 14

COMPLETE C PROGRAM

Complete C implementation

#include <stdio.h>

int main(void)
{
    int number, sum;

    printf("Enter a three-digit positive integer: ");
    scanf("%d", &number);
    sum = number / 100 + (number / 10) % 10 + number % 10;
    printf("Digit sum = %d\n", sum);
    return 0;
}

CURRENT STEP

Select Start to walk through the important lines.

SELECTED LINE

No line selected

EXPECTED OUTPUT FOR THE SAMPLE

Digit sum = 14

0%Step 0 of 0

PROGRAM EXPLANATION

Algorithm and explanation

Read the required input values.
Extract hundreds, tens and ones with division and remainder, then add them.
Display the computed result.

Extract hundreds, tens and ones with division and remainder, then add them.

EFFICIENCY

Time and space complexity

Time complexity

O(1)

Auxiliary space

O(1)

DEBUGGING CHECKLIST

Common mistakes

Check this

Use the correct format specifier for every variable.

Check this

Initialize variables before using their values.

Check this

Check braces, semicolons and input order carefully.

Try it yourself

Practice: Run the program with the sample input, predict its output, and then test one boundary case of your own.