How do you add last digit of two numbers in python?

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

String Representation

Python3

number = 1247

number = str(number)

first_digit = int(number[0])

last_digit = int(number[-1])

addition = first_digit + last_digit

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

number = 1247

res = number % 10

while number > 9:

    number = number // 10

res += number

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

This Python program calculates sum of first and last digit of a given number.

In this program, we first read number from user. Then we reverse it using [::-1]. After reversing, we convert both number & reverse to integer using int() function. first_digit is obtained by reverse%10 and last_digit is obtained by number%10. Finally we calculate sum of first & last digit to get final result.

Python Source Code: Sum of First & Last Digit

# Sum of first & last digit

# Reading number
number  = input("Enter number: ")

# Reversing number
reverse = number[::-1]

# Converting number and its reverse to integer
number = int(number)
reverse = int(reverse)

# Finding first digit
first_digit = reverse % 10

# Finding last digit
last_digit = number % 10

# Finding sum
total_sum = first_digit + last_digit

# Displaying sum
print("Sum of first & last digit of %d is %d" %(number, total_sum))

Output

Enter number: 99975
Sum of first & last digit of 99975 is 14