In Python, you can get the last digit of an integer in the following ways:

## Using Modulo Operator

You can use the modulo operator (`%`

) to get the last digit of an integer in the following way:

- Convert number to absolute form;
- Get the last digit by calculating
`number % 10`

; - Add negative sign to the last digit if integer was negative.

The modulo operator in Python *won't* return the correct last digit for negative numbers because it performs floored division, and not truncated division. To get the correct result, you *must* convert the number to absolute form first (using `abs()`

), and then add the sign back.

For example:

def last_digit(num): last_digit_unsigned = abs(num) % 10 return -last_digit_unsigned if (num < 0) else last_digit_unsigned print(last_digit(0)) # 0 print(last_digit(1234)) # 4 print(last_digit(-1234)) # -4

As an alternative, you may use the following mathematical formula for calculating remainder correctly:

def last_digit(num): return num - (10 * int(num / 10)) print(last_digit(0)) # 0 print(last_digit(1234)) # 4 print(last_digit(-1234)) # -4

This performs truncated division (i.e. using the `int()`

method, the fraction part is removed/truncated from the result of the division).

This works in the following way:

# num = 1234 # last_digit = 1234 - (10 * int(1234 / 10)) # last_digit = 1234 - (10 * int(123.4)) # last_digit = 1234 - (10 * 123) # last_digit = 1234 - 1230 # last_digit = 4

## Converting to String and Retrieving Last Character

You could do the following:

- Convert the integer to a string;
- Get the last character of the string;
- Convert the string back to integer;
- Add negative sign to the last digit if integer was negative.

def last_digit(num): num_str = str(num) last_digit_unsigned = int(num_str[-1]) return -last_digit_unsigned if (num < 0) else last_digit_unsigned print(last_digit(0)) # 0 print(last_digit(1234)) # 4 print(last_digit(-1234)) # -4

When the integer is converted to a string, the sign is considered a character in the string and has *no* special meaning, which is why it is *not* added to the last digit. For this reason, the sign is added back once the last character is converted back to an integer.

This post was published by Daniyal Hamid. Daniyal currently works as the Head of Engineering in Germany and has 20+ years of experience in software engineering, design and marketing. Please show your love and support by sharing this post.