How to reverse a number in Python?

Reversing an integer number is an easy task. We may encounter certain scenarios where it will be required to reverse a number.

Input: 12345
Output: 54321

There are two ways, we can reverse a number −

• Convert the number into a string, reverse the string and reconvert it into an integer

• Reverse mathematically without converting into a string

Convert into string and Reverse

This method of reversing a number is easy and doesn’t require any logic. We will simply convert the number into string and reverse it and then reconvert the reversed string into integer. We can use any suitable method for reversing the string.

Example

 Live Demo

def reverse(num):
   st=str(num)
   revst=st[::-1]
   ans=int(revst)
   return ans
num=12345
print(reverse(num))

Output

54321

Reverse mathematically without converting into string

This method requires mathematical logic. This method can be used when there is a restriction of not converting the number into string.

Example

 Live Demo

def reverse(num):
   rev=0
   while(num>0):
      digit=num%10
      rev=(rev*10)+digit
      num=num//10
   return rev
num=12345
print(reverse(num))

Output

54321

pawandeep

Updated on: 10-Mar-2021

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