# 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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