How do i 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.

Table of Contents Show

Convert into string and Reverse
Reverse mathematically without converting into string
Can you reverse an integer Python?
How do you reverse a number?
How do you reverse input in Python?

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

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

Updated on 10-Mar-2021 14:12:28

Related Questions & Answers
How to reverse a string in Python?
Reverse a number in JavaScript
How to create reverse of a number in R?
C++ Program to Reverse a Number
Java Program to Reverse a Number
Python program to reverse bits of a positive integer number?
How to reverse a string in Python program?
Reverse a Number in PL/SQL
Write a Golang program to reverse a number
Reverse a number using stack in C++
How to reverse the objects in a list in Python?
Write a program to reverse digits of a number in C++
Program to reverse a linked list in Python
Python program to Reverse a range in list
Python program to reverse a Numpy array?

This is a Python Program to reverse a given number.

Problem Description

The program takes a number and reverses it.

Problem Solution

1. Take the value of the integer and store in a variable.
2. Using a while loop, get each digit of the number and store the reversed number in another variable.
3. Print the reverse of the number.
4. Exit.

Program/Source Code

Here is the source code of the Python Program to reverse a given number.

 
n=int(input("Enter number: "))
rev=0
while(n>0):
    dig=n%10
    rev=rev*10+dig
    n=n//10
print("Reverse of the number:",rev)

Program Explanation

1. User must first enter the value and store it in a variable n.
2. The while loop is used and the last digit of the number is obtained by using the modulus operator.
3. The last digit is then stored at the one’s place, second last at the ten’s place and so on.
4. The last digit is then removed by truly dividing the number with 10.
5. This loop terminates when the value of the number is 0.
6. The reverse of the number is then printed.

Runtime Test Cases

 
Case 1:
Enter number: 124
Reverse of the number: 421
 
Case 2:
Enter number: 4538
Reverse of the number: 8354

Sanfoundry Global Education & Learning Series – Python Programs.

To practice all Python programs, here is complete set of 150+ Python Problems and Solutions.

Next Steps:

Get Free Certificate of Merit in Python Programming
Participate in Python Programming Certification Contest
Become a Top Ranker in Python Programming
Take Python Programming Tests
Chapterwise Practice Tests: Chapter 1, 2, 3, 4, 5, 6, 7, 8, 9, 10
Chapterwise Mock Tests: Chapter 1, 2, 3, 4, 5, 6, 7, 8, 9, 10

Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He lives in Bangalore, and focuses on development of Linux Kernel, SAN Technologies, Advanced C, Data Structures & Alogrithms. Stay connected with him at LinkedIn.

Subscribe to his free Masterclasses at Youtube & technical discussions at Telegram SanfoundryClasses.

Can you reverse an integer Python?

Python makes it easy to reverse a number by using a while loop. We use a while loop with the help of both floor division and the modulus % operator.

How do you reverse a number?

Reverse an Integer In each iteration of the loop, the remainder when n is divided by 10 is calculated and the value of n is reduced by 10 times. Inside the loop, the reversed number is computed using: reverse = reverse * 10 + remainder; Let us see how the while loop works when n = 2345 .

How do you reverse input in Python?

Use reversed() Method to Reverse a String in Python You can also use the reversed method in Python which returns a reversed object or iterator of the input string. The only thing you need to do is to perform an additional join operation on the resultant reversed object and return the new string.