C program to find sum of first and last digit of a number

Category: C Program

Learn how to write a C program to find the sum of the first and last digit of a number. This article provides a detailed explanation and sample code for this basic yet essential task in C programming.

Finding the sum of the first and last digits of a number is a common problem in programming that helps in understanding basic arithmetic operations and control structures. In this article, we will guide you through writing a C program to find the sum of the first and last digits of a given number, providing a detailed explanation and sample code.

Steps to Find the Sum of the First and Last Digit

To solve this problem, follow these steps:

1. Input the Number: Read the number from the user.
2. Extract the Last Digit: Find the number's last digit using the modulus operator.
3. Extract the First Digit: Find the first digit by continuously dividing the number by 10 until the number is less than 10.
4. Calculate the Sum: Add the first and last digits.
5. Print the Result: Output the sum to the console.

Write a C program to find sum of first and last digits of a number

Here's a C program to find the sum of the first and last digit of a number:

``````#include <stdio.h>

int main() {
int number, firstDigit, lastDigit, sum;

// Input the number
printf("Enter an integer: ");
scanf("%d", &number);

// Extract the last digit
lastDigit = number % 10;

// Extract the first digit
firstDigit = number;
while (firstDigit >= 10) {
firstDigit /= 10;
}

// Calculate the sum
sum = firstDigit + lastDigit;

// Print the result
printf("Sum of the first and last digit: %d", sum);

return 0;
}
``````

Output

``````Enter an integer: 1234
Sum of the first and last digit: 5
``````

Explanation

1. Input the Number: The program prompts the user to enter an integer. The `scanf` function reads the input number and stores it in the variable `number`.
2. Extract the Last Digit:
• The last digit is found using the modulus operator (`%`), which gives the remainder when `number` is divided by 10.
• For example, if the number is 1234, `lastDigit = 1234 % 10` will result in `lastDigit = 4`.
3. Extract the First Digit:
• The first digit is found by repeatedly dividing the number by 10 until it is less than 10.
• For example, if the number is 1234, the sequence of operations will be `1234 / 10 = 123`, `123 / 10 = 12`, `12 / 10 = 1`, resulting in `firstDigit = 1`.
4. Calculate the Sum: The sum of the first and last digits is calculated by adding `firstDigit` and `lastDigit`.
5. Print the Result: The program prints the sum to the console using the `printf` function.

Detailed Steps

• Step 1: Input the Number
• Use `printf` to prompt the user for input.
• Use `scanf` to read the number from the user.
• Step 2: Extract the Last Digit
• Use the modulus operator (`%`) to get the last digit of the number.
• Step 3: Extract the First Digit
• Use a `while` loop to divide the number by 10 until it is less than 10.
• Step 4: Calculate the Sum
• Add the first and last digits.
• Step 5: Print the Result
• Use `printf` to display the sum of the first and last digits.