Programiz
programiz.com › python-programming › examples › reverse-a-number
Python Program to Reverse a Number
Python slice() Python range() Function ... while loop is used to reverse a number as given in the following steps: First, the remainder of the num divided by 10 is stored in the variable digit....
GeeksforGeeks
geeksforgeeks.org › python › python-program-to-reverse-a-number
Python Program to Reverse a Number - GeeksforGeeks
November 18, 2025 - This method reverses the number by converting it to a string, slicing it in reverse order and converting it back to an integer. ... This method extracts digits from the end of the number using % 10 and builds the reversed number digit-by-digit.
slice - Reversing a negative number in Python - Stack Overflow
Using slice method in Python we are able to reverse strings and numbers easily. However, how could it be done when the number is negative? def reverse(x): string = str(x) return int(string... More on stackoverflow.com
Reversing a list using slice
You've asked a very interesting question. Does the first colon(:) mean we start at the beginning, and the second colon(:) mean we end also at the beginning? This is an incorrect framing. The VALUE before the first colon is the beginning and the VALUE after the first colon is the ending. The value after the second colon is the step count. Another thing to keep in mind that the default start and stop values are None. So this is what we end up with: [::-1] == [None:None:-1] >>>alist = [1,2,3] >>>alist[None:None:-1] [3,2,1] People often teach default start and stop values as 0 and len(alist) but that's entirely incorrect. This will actually return an empty list. >>>alist[0:len(alist):-1] [] Now we come to another interesting question. What does [None:None:-1] actually do? I've no clue. Afaik there is no way to return a reversed list if the Stop value isn't None. Which is fucking INSANE. >>>alist[-1:None:-1] [3,2,1] >>>alist[-1:-1:-1] [] >>>alist[-1:0:-1] [3,2] >>>alist[-1:len(alist):-1] [] >>>alist[-1:len(alist)-1:-1] [] >>>alist[len(alist)-1:0:-1] [3, 2] >>>alist[len(alist)-1:-1:-1] ##Should work right? But Nope. [] If someone here knows how to slice reverse, without using or implying None, please tell me. More on reddit.com
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December 23, 2023Fastest way to reverse a string - and it's not extended string splicing?
I was told there's a faster method with some optimisations possible. If reversing strings is a bottleneck needing optimization, then your codebase might have bigger issues. More on reddit.com
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August 12, 20207 proven methods to reverse the python string in 2021
"".join(sorted(a, reverse=True)) will not reverse a string. >>> a = "hello world" >>> "".join(sorted(a, reverse=True)) 'wroolllhed ' There's a deeper problem with articles like this, though. Reversing a string is a trivial task (i.e., it's something for a beginner to learn). Giving seven different methods with no explanation on if one is better than another is not good teaching, especially when some don't even work and others are pointlessly verbose. More on reddit.com
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December 4, 2021Videos
07:49
Python Program #80 - Reverse a Number in Python - YouTube
08:20
Reverse a Number - Coding Challenge - YouTube
Python Program to print reverse of the number using defined function ...
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Python Program to Reverse a Number ( using String Method Tutorial ...
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How to create a reversed copy of a list using reverse slicing in ...
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How to reverse a number using slice operations in python || ...
Medium
medium.com › programminginpython-com › python-program-to-find-reverse-of-a-number-using-slice-83a04eb9e00e
Python program to find reverse of a number using slice | by Avinash Nethala | programminginpython.com | Medium
March 30, 2017 - We convert that integer number to string str(num). Now we use advanced slice operation [start:end:step] leaving start and empty and giving step a value of -1, this slice operation reverses the string.
PYnative
pynative.com › home › python › programs and examples › python programs to reverse an integer number
Python Reverse a Number [4 Ways] – PYnative
March 31, 2025 - num = 123456 # Convert the integer to string and reverse it using slicing reversed_str = str(num)[::-1] # Handle negative numbers if num < 0: reversed_int = int('-' + reversed_str[:-1]) # Exclude the last character which is '-' else: reversed_int = int(reversed_str) print('Reversed Integer:', ...
Scaler
scaler.com › home › topics › reverse a number in python
Reverse a Number in Python - Scaler Topics
June 21, 2024 - Slicing is obtaining the substring of a string in python. The exciting thing about slicing is that if we use -1 as a parameter, we can obtain the substring from the end, thus reversing the number.
Python Examples
pythonexamples.org › reverse-a-number-in-python
Reverse a Number in Python
In this program we shall use while loop to iterate over the digits of the number by popping them one by one using modulo operator. Popped digits are appended to form a new number which would be our reversed number. n = 123456 reversed = 0 while(n!=0): r=int(n) reversed = reversed*10 + r ...
Sanfoundry
sanfoundry.com › python-program-reverse-given-number
Reverse a Number in Python - Sanfoundry
June 21, 2023 - Testcase 2: In this case, we are entering the number “4538” as input. ... In this approach, we will use slice operator [::-1] to reverse the string. ... Here is the source code of the Python Program to reverse a given number using Slice Operator.
Newtum
blog.newtum.com › home › reverse a number in python using string slicing
Reverse a Number in Python Using String Slicing | Newtum
April 25, 2024 - The syntax for string slicing in Python is as follows: string[start:end:step]. By specifying the appropriate start, end, and step values, we can create new strings that contain the desired portion of the original string.
PREP INSTA
prepinsta.com › home › python program › reverse a number in python
Reverse of a number in Python | PrepInsta
July 29, 2023 - First we’ll convert the number into a string and then using the string slicing property in python language, we’ll slice the string to break it down and add it up in reverse order.
Tutorial Gateway
tutorialgateway.org › python-program-to-reverse-a-number
Python Program to Reverse a Number
April 7, 2025 - To reverse a number, first, you must find the last digit in a number. Next, add it to the first position of the other variable, then remove that last digit from the original number.
Educative
educative.io › answers › how-to-reverse-a-given-number-in-python
How to reverse a given number in Python
Now that we understand how to reverse a number using a while loop, let’s explore Python’s string slicing capabilities to provide a more straightforward approach to reversing a number. In this approach, after taking the input number from the user, we first check if it is negative and store this information.
Upgrad
upgrad.com › home › tutorials › software & tech › reverse a number in python
How to Reverse a Number in Python: 5 Smart Ways with Code
November 11, 2024 - You can reverse a number in Python ... The simplest way is to use a for loop combined with slicing or the reversed() function to iterate through the digits in reverse and construct the reversed number....
EDUCBA
educba.com › home › software development › software development tutorials › python tutorial › reverse number in python
Reverse Number in Python | Top12 Methods of Reverse Number in Python
April 17, 2023 - There are multiple pre-defined methods in python which can be worked along with the conditional statements for creating reverse logical function, and they are list method, slice method, recursion method, etc. Reverse() method is the straightforward method for performing this operation for any kind of input provided by the user. ... Valuation, Hadoop, Excel, Mobile Apps, Web Development & many more. The below points briefly us about how to reverse a given number ...
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Vultr
docs.vultr.com › python › examples › reverse-a-number
Python Program to Reverse a Number | Vultr Docs
December 9, 2024 - You'll explore this through a series ... the nuances of each method. Start by converting the number to a string. Use string slicing to reverse the string....
Django Central
djangocentral.com › reverse-a-number
Python Program To Reverse a Number
The step parameter is used to specify the steps to take from the start to end index. ... Since slicing work on a string we need to convert the number to a string, then create a slice that starts with the length of the string, and ends at index 0 with a step of -1.
Python Guides
pythonguides.com › reverse-a-number-in-python
How To Reverse A Number In Python?
March 20, 2025 - In this tutorial, I explained how to reverse a number in Python. I discussed some methods such as the string conversion approach, mathematical approach, recursion, list comprehension and join(), the reversed() function, reduce() function, one-loner using extended slice syntax, and using generators ...
W3Schools
w3schools.com › python › python_howto_reverse_string.asp
How to reverse a String in Python
Remove List Duplicates Reverse ... to reverse a String in Python. The fastest (and easiest?) way is to use a slice that steps backwards, -1....
TutorialsPoint
tutorialspoint.com › article › how-to-reverse-a-number-in-python
How to reverse a number in Python?
This method converts the number to a string, reverses it using Python's slice notation [::-1], and converts back to integer ? def reverse_string_method(num): st = str(num) revst = st[::-1] ans = int(revst) return ans num = 12345 print(reverse_string_method(num)) 54321 · num = 12345 reversed_num = int(str(num)[::-1]) print(reversed_num) 54321 · This method uses mathematical operations to extract digits from right to left and build the reversed number ?
NxtWave
ccbp.in › blog › articles › reverse-a-number-in-python
Reverse a Number in Python: Methods & Best Practices
On the other hand, mathematical operations provide a more algorithmic approach to manipulating digits instead of converting the number to a string. In addition, Python has built-in options like the reversed() function or the use of list slicing, which allows for a clean and straightforward solution for reversing numbers.
Top answer 1 of 3
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Assuming that you want to preserve the sign, try this:
def reverse(x):
ans = int(str(x)[::-1]) if x >= 0 else -int(str(-x)[::-1])
return ans if -2**31 <= ans <= 2**31 - 1 else 0
It works as expected for all the edge cases introduced by the new requirements:
reverse(321)
=> 123
reverse(-321)
=> -123
reverse(120)
=> 21
reverse(-120)
=> -21
reverse(7463847412)
=> 2147483647
reverse(8463847412)
=> 0
reverse(-8463847412)
=> -2147483648
reverse(-9463847412)
=> 0
2 of 3
1
I have posted the unwrapped, simplified code to make it easier to understand the answer:
def int_reverser(test):
if test >= 0:
answer = int(str(test)[::-1])
else:
answer = -int(str(-test)[::-1])
if -2**31 <= answer <= 2**31 - 1:
return answer
else:
return 0