Easy C Program to Calculate the Sum of Digits in a Three-Digit Number

#include <stdio.h>
int main() {
int number, digit1, digit2, digit3, sum;
// Ask the user to enter a three-digit number
printf("Enter a three-digit number: ");
scanf("%d", &number);

// Extract digits
// First digit (hundreds place)
digit1 = number / 100;

// Second digit (tens place) digit2 = (number / 10) % 10;

// Third digit (units place) digit3 = number % 10;
// Calculate the sum
sum = digit1 + digit2 + digit3;
// Print the result
printf("The sum of digits is: %d\n", sum);
return 0;
}

Output:
Enter a three-digit number: 456
The sum of digits is:15
Description:
This simple C program calculates the sum of digits of a three-digit number.
Let us analyze this program step by step in layman's terminology.

1. Including the Header File
#include <stdio.h>
We include the standard input-output library, which has functions like printf() and scanf() to enable the user input and output.

2. Main function
int main()
This is the starting point of a program. All the logic will be contained in this function.

3. Declaring Variable
int number, digit1, digit2, digit3, sum;
Here is what these variables do:
number: this variable stores the number entered by the user
digit1, digit2, digit3: these three variables hold each digit separately
sum: this variable stores the final sum of those digits

4. Accepting the User Input
printf("Enter a three-digit number: ");
scanf("%d", &number);
The program demands a user input of a three-digit number and stores it in number.

5. Breaking the Number into Digits
digit1 = number / 100;
digit2 = (number / 10) % 10;
digit3 = number % 10;
In brief, the function of each line is as follows:
digit1: gets the hundreds digit
digit2: gets the middle digit
digit3: gets the last digit

Example. For, 456:
digit1 = 456 / 100 = 4
digit2 = (456 / 10) % 10 = 5
digit3 = 456 % 10 = 6

6. The Sum Calculation
sum = digit1 + digit2 + digit3;
Now we add all three digits together and keep their result in sum.

7. Result Display
printf("The sum of digits is: %d\n", sum);
And finally, we print the result out on the screen.
An Output Example:
When 456 is entered into the program, it returns:
The sum of digits is: 15.

Basic and Operators practice program assignments in C Language :
Practice/Assignment set 1:
1.Write a program in C to Input integer, float and character values using one scanf().
2.Write a program in C language to find the Area of Circle.
3.Write a program in C language to Input an integer value and print with padding by Zeros in C
4. Write a program in C language to Input float value and print it with specified digit after decimal point in C
6. Write a program in C language to Input an unsigned integer value using scanf().
7.Write a program in C language to Find area of Triangle
8.Write a program in C language to Input a hexadecimal value using scanf() in C
9.Write a program in C language to Input octal value using scanf()
10.Write a program in C language to Convert temperature given in farenheight to degree celcius.
11.Write a program in C language to Input octal value using scanf()
12.Write a program in C language to Input decimal, octal and hexadecimal values in character variables using scanf() in C
13.Write a program in C language to Input an integer value in any format (decimal, octal or hexadecimal) using '%i' in C
14.Write a program in C language to Input side value and find area of Square.
15.Write a program in C language to Input individual characters using scanf() in C
16.Write a program in C language to Read a memory address using scanf() and print its value in C
17.Write a program in C language to Skip characters while reading integers using scanf() in C
18.Print your name, date of birth, and mobile number
19. Write a C program to convert specified days into years, weeks and days. Note: Ignore leap year.

21.Write a C program that accepts two item's weight and number of purchases (floating point values) and calculates their average value.

22.Write a C program that accepts an employee's ID, total worked hours in a month and the amount he received per hour. Print the ID and salary (with two decimal places) of the employee for a particular month.
Test Data :
Input the Employees ID(Max. 10 chars): 0342
Input the working hrs: 8
Salary amount/hr: 15000
Expected Output:
Employees ID = 0342
Salary = U$ 120000.00

23.Write a C program that accept an students roll number and six subject markes, find total and average marks.

24.Write a C program that accepts an employee's ID, basic salary in a month and calculate total salary.
The formulat for
Total salary=(basic salary-tax)+House Rent allowance+Bonus+Traveling allowance+other allowance
tax 10% of basic salary
House Rent allowance 17% of basic salary
Bonus 7% of basic salary
Traveling allowance 8% of basic salary
other allowance 10% of basic salary
25.Write a C program to convert a given integer (in days) to years, months and days, assuming that all months have 30 days and all years have 365 days.
Test Data :
Input no. of days: 2535
Expected Output:
6 Year(s)
11 Month(s)
15 Day(s)

Practice/Assignment set 2:
1. C program to find sum of the square of all natural numbers from 1 to N.
Series: 1^2+2^2+3^2+4^2+..N^2
2. C program to find sum of the all natural numbers from 1 to N.
Series: 1+2+3+4+..N
3.C program to find the sum of Natural Number/Factorial of Number of all natural numbers from 1 to N.
Series: 1/1! + 2/2! + 3/3! + 4/4! + ... N/N!
4) C program to find sum of following series:
1+ 1/2 + 1/3 + 1/4 + 1/5 + .. 1/N
5) C program to find sum of following series:
1 + 3^2/3^3 + 5^2/5^3 + 7^2/7^3 + ... till N terms