# C program to find sum of first and last digit of any number

Write a C program to input a number and find sum of first and last digit of the number using for loop. How to find sum of first and last digit of a number in C programming using loop. Logic to find sum of first and last digit of a number without using loop in C program.

Example

Input

`Input number: 12345`

Output

`Sum of first and last digit: 6`

## Logic to find sum of first and last digit using loop

Step by step descriptive logic to find sum of first and last digit using loop.

1. Input a number from user. Store it in some variable say num.
2. To find last digit of given number we modulo divide the given number by 10. Which is `lastDigit = num % 10`.
3. To find first digit we divide the given number by 10 till num is greater than 0.
4. Finally calculate sum of first and last digit i.e. `sum = firstDigit + lastDigit`.

## Program to find sum of first and last digit using loop

``````/**
* C program to find sum of first and last digit of a number using loop
*/

#include <stdio.h>

int main()
{
int num, sum=0, firstDigit, lastDigit;

/* Input a number from user */
printf("Enter any number to find sum of first and last digit: ");
scanf("%d", &num);

/* Find last digit to sum */
lastDigit = num % 10;

/* Copy num to first digit */
firstDigit = num;

/* Find the first digit by dividing num by 10 until first digit is left */
while(num >= 10)
{
num = num / 10;
}
firstDigit = num;

/* Find sum of first and last digit*/
sum = firstDigit + lastDigit;

printf("Sum of first and last digit = %d", sum);

return 0;
}``````

## Program to find sum of first and last digit without using loop

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

#include <stdio.h>
#include <math.h>

int main()
{
int num, sum, digits, firstDigit, lastDigit;

sum = 0;

/* Input a number from user */
printf("Enter any number to find sum of first and last digit: ");
scanf("%d", &num);

/* Find last digit */
lastDigit  = num % 10;

/* Find total number of digits - 1 */
digits    = (int) log10(num);

/* Find first digit */
firstDigit = (int) (num / pow(10, digits));

/* Calculate the sum */
sum = firstDigit + lastDigit;

printf("Sum of first and last digit = %d", sum);

return 0;
}``````

In the above program I have used two mathematical function `pow()` and `log10()`. Both the function are present in `math.h` header file.

Output

```Enter any number to find sum of first and last digit: 12345
Sum of first and last digit = 6```

Happy coding ðŸ˜‰