Python Program to Reverse a Number

In this article, we will explore two techniques for reversing a number in Python. Various methods exist for creating a Python program to reverse a number, and we will elucidate some commonly employed approaches in this discussion.

Example:

Input: 1234
Output: 4321

Python Program to Reverse a Number

Below are examples of how to reverse a number using a Python program.

• Using For Loop
• Using While loop
• Using Recursion
• Using String Slicing

Reverse a Number Using For Loop

In this example, in the below code Python function `reverse_number` reverses a given number by iterating through its digits using a for loop. It prints the original and reversed numbers. In the example, the function is applied to the number 6789.

Python3

def reverse_number(number):
    original_number = number
    reverse = 0

    for _ in str(number):
        digit = number % 10
        reverse = reverse * 10 + digit
        number //= 10

    print(f"Original Number: {original_number}")
    print(f"Reversed Number: {reverse}")

# Example Usage
reverse = 6789
reverse_number(reverse)

Output :

Original Number: 6789
Reversed Number: 9876

Reverse a Number Using While Loop

In this example, in below code Python code defines a function `reverse_number` that reverses a given number using a while loop. It prints the original and reversed numbers. The example demonstrates applying the function to the number 6789.

Python3

def reverse_number(number):
    original_number = number
    reverse = 0

    while number > 0:
        digit = number % 10
        reverse = reverse * 10 + digit
        number //= 10

    print(f"Original Number: {original_number}")
    print(f"Reversed Number: {reverse}")

# Example Usage
reverse = 6789
reverse_number(reverse)

Output :

Original Number: 6789
Reversed Number: 9876

Reverse a Number Using Recursion

In this example, in below code Python function `reverse_number` recursively reverses a given number by extracting the last digit and placing it at the appropriate position. The recursion continues until the original number is fully reversed. The example demonstrates reversing the number 987654.

Python3

def reverse_number(number):
    if number == 0:
        return 0
    else:
        return (number % 10) * 10 ** (len(str(number)) - 1) + reverse_number_recursion(number // 10)

# Example Usage
reverse = 987654
original_number = reverse
reversed_number = reverse_number(reverse)
print(f"Original Number: {original_number}")
print(f"Reversed Number: {reversed_number}")

Output :

Original Number: 987654
Reversed Number: 456789

Reverse a Number Using String Slicing

In this example, in below code Python code defines a function `reverse_number` that reverses a given number using a list to manipulate its digits. The original and reversed numbers are then printed for an example case where the original number is 1234.

Python3

def reverse_number(number):
    num_list = list(str(number))
    reversed_num = int(''.join(num_list[::-1]))
    return reversed_num

original_number = 1234
result = reverse_number(original_number)
print("Original Number:", original_number)
print("Reversed Number (List):", result)

Output :

Original Number: 1234
Reversed Number (List): 4321