# Python Program to Find Sum of First and Last Digit

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 usingstring[0]and the last element of String usingstring[-1].

## 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