How to Reverse a Number in Python Using a WHILE Loop

In this tutorial, we’ll be demonstrating how to reverse a number in Python using a while loop. The while loop is one of the most basic control flow structures in Python, which allows a certain section of code to be executed until a certain condition is met. In this case, we’ll utilize it to accurately reverse the digits of an input number.

Step 1: Understand the Problem

Before we write the code needed to reverse a number, we first need to understand what reversing a number means. It simply implies changing the order of the digits of a number to its opposite. For instance, given the number 12345, the reversed number would be 54321.

Step 2: Acquiring User Input

Finding a solution to a problem is one thing, but we need a means of testing it. For our code, we need to obtain a number to reverse via user input. Here’s how we can acquire an integer input from a user.

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num = int(input("Enter a number: "))

Step 3: Implementing the While Loop

With the user input in place, we can now proceed to reverse the number. Below is the Python code to reverse a number using a while loop.

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rev = 0
 
while num > 0:
    a = num % 10
    rev = rev * 10 + a
    num = num // 10
 
print("The reversed number is : ", rev)

Step 4: Testing the Code

After writing our code, it’s crucial we test it using several test cases to ensure it works as anticipated. Test it by inputting different numbers and observing the output.

Step 5: Understanding the Code

The code works by iteratively taking the last digit of the number and appending it to the reversed number. This is done until there are no more digits left in the number to reverse.

Complete Python Code to Reverse a Number Using a While Loop

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num = int(input("Enter a number: "))
rev = 0
 
while num > 0:
    a = num % 10
    rev = rev * 10 + a
    num = num // 10
 
print("The reversed number is : ", rev)

Conclusion

In this tutorial, we have utilized Python’s while loop control structure to reverse a number. It’s a simple piece of code but one that fundamentally leverages the logic behind the while loop. Remember to run the code and observe the results. Happy coding!