C Program to Find Sum of First and Last Digits of a Number

  • Write a C program to find sum of first and last digits of a number.
  • Wap in C to find sum of least significant and most significant digit of a number.

Required Knowledge

To get the least significant digit of a number we will use '%' modulus operator. Number%10 will give the least significant digit of the number. Then we will remove one digit at a time form number using below mentioned algorithm and then store the most significant digit in firstDigit variable.
Sum of first and last digits of 2534 = 2 + 4 = 6

Algorithm to find first and last digits of a number
  • Get least significant digit of number (number%10) and store it in lastDigit variable.
  • Remove least significant digit form number (number = number/10).
  • Repeat above two steps, till number is greater than 10.
  • The remaining number is the first digit of number.

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

#include <stdio.h>

int main() {  
    int num, temp, firstDigit, lastDigit;  
  
    /* 
     * Take a number as input from user
     */  
    printf("Enter a Number\n"); 
    scanf("%d", &num);  
    temp = num;
    
    /* get last digit of num */
    lastDigit = num %10;
    
    while(num > 10){
        /* Keep on removing the last digit untill 
         num becomes less than 10(single digit) */
        num = num/10;
    } 
    firstDigit = num;
    printf("Sum of first and last digit of %d = %d", temp, firstDigit+lastDigit);  
  
    getch();
    return 0;  
}

Output
Enter a Number
2436
Sum of first and last digit of 2436 = 8
Enter a Number
2222
Sum of first and last digit of 2222 = 4
Write a C program to find product of digits of a number using while loop.
Wap in C to multiply the digits of a number.

Required Knowledge

To multiply digits of a number we have to remove one digit at a time, we can use '/' division and '%' modulus operator. Number%10 will give the least significant digit of the number, we will use it to get one digit of number at a time. To remove last least significant digit from number we will divide number by 10.

Product of digits of 2534 = 2 x 5 x 3 x 4 = 120

Algorithm to find product of digits of a number
  • Get least significant digit of number (number%10) and multiply it to the product variable.
  • Remove least significant digit form number (number = number/10).
  • Repeat above two steps, till number is not equal to zero.

C program to find sum of all even numbers between 1 to N using for loop

#include <stdio.h>
#include <conio.h>  
  
int main() {  
    int num, temp;  
    long productOfDigit = 1;  
  
    /* 
     * Take a number as input from user
     */  
    printf("Enter a Number\n");  
    scanf("%d", &num);  
    temp = num;
    
    while(num != 0){
        /* get the least significant digit(last digit) 
         of number and multiply it to productofDigit */
        productOfDigit *= num % 10;
        /* remove least significant digit(last digit)
         form number */
        num = num/10;
    } 
  
    printf("Product of digits of %d = %ld", temp, productOfDigit);  
  
    getch();
    return 0;  
}

Output
Enter a Number
2436
Product of digits of 2436 = 144
Enter a Number
2222
Product of digits of 2436 = 16

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