# Python Program to Find Sum of First and Last Digit

• Difficulty Level : Hard
• Last Updated : 02 Aug, 2022

Given a positive integer N(at least contain two digits). The task is to write a Python program to add the first and last digit of the given number N.

Examples:

```Input: N = 1247
Output: 8

Explanation: First digit is 1 and Last digit is 7.
So, addition of these two (1 + 7) is equal to 8.```
```Input: N = 73
Output: 10```

### Method 1: String implementation

• Take input in the form of String or typecast given input in String.
• Now pick the 0th index of the String and typecast it into Integer and store it in a variable.
• The same thing with the -1st index and also store in another variable.
• Now add these two variables and
• print them as an Output.

Note:  We can access the first element of String using string and the last element of String using string[-1]. String Representation

## Python3

 `# We have a number``number ``=` `1247` `# We are type casting it in string``number ``=` `str``(number)` `# Storing first and last digit in a variable``# after type casting into Integer.``first_digit ``=` `int``(number[``0``])``last_digit ``=` `int``(number[``-``1``])` `# Adding these two variables``addition ``=` `first_digit ``+` `last_digit` `# Display our output``print``(``'Addition of first and last digit of the number is'``,``      ``addition)`

Output:

Addition of first and last digit of the number is 8

Time complexity: O(1) since performing constant operations

Auxiliary Space: O(1) since using constant space for variables

### Method 2: Solve it using an integer

• We have given a positive Integer.
• After dividing by 10, store the remainder in a result variable.
• Continue the loop until the number becomes less than 9.
• Each time in the loop, divide the number by 10(integer division).
• After the end of the loop.
• Add the number in the result variable.
• Display the result variable as the output.

Note: Whenever we divide any number with 10, we get the last digit as the remainder. If we divide any number with 100, we get the last two-digit as the remainder.

## Python3

 `# We have a number.``number ``=` `1247` `# Assigning last digit of the number in res``# variable.``res ``=` `number ``%` `10` `# Now, continue a loop until``# the number becomes less than 9.``while` `number > ``9``:` `    ``# integer division of the number and reassigning``    ``# it.``    ``number ``=` `number ``/``/` `10` `# Here, our number only contain one digit.``# So, add this number in res variable.``res ``+``=` `number` `# Now, display our output``print``(``'Addition of first and last digit of number is'``, res)`

Output:

`Addition of first and last digit of the number is 8`

Time Complexity: O(n), where n is how many digits are there in the given number.

Auxiliary Space: O(1) since using constant space for variables

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