**Python Programs**

Python Flow Control

➤ Even Number in Python

➤ Odd Number in Python

➤ Even Odd Program

➤ Largest of 3 Numbers

➤ Leap Year Program

➤ Multiplication Table

➤ Factors of a Number

➤ Prime Factors in Python

➤ Factorial of a Number

➤ Factorial using Function

➤ Math.factorial() in Python

➤ Factorial using Recursion

➤ LCM of Two Numbers

➤ HCF/GCD of 2 Numbers

➤ Solve Quadratic Equation

➤ Sum of Digits of a Number

➤ Sum of N Natural Numbers

➤ Fibonacci Series in Python

➤ Fibonacci Series – Recursion

➤ Simple Calculator in Python

➤ Perfect Square in Python

➤ Absolute Value in Python

Conversion Programs

➤ Celsius to Fahrenheit

➤ Fahrenheit to Celsius

➤ Decimal to Binary

➤ Binary to Decimal

➤ Decimal to Octal

➤ Octal to Decimal

➤ Decimal to Hexadecimal

➤ Hexadecimal to Decimal

Array Programs

➤ Linear Search in Python

➤ Binary Search in Python

We can reverse a number in python using different methods. To reverse a number we need to extract the last digit of the number and add that number into a temporary variable with some calculation, then remove the last digit of the number. Do these processes until the number becomes zero.

To remove the last digit the modulus operator (%) will be helpful for us, and to remove the last digit division operator (/) can be used. To add the last digit first we need to multiply the previous value by 10. Once you get the logic, you can write the program in any language.

**Example** of the reverse a number:-

Number: 12345

Reverse number: 54321

**Procedure to find reverse of a number**,

- Take a number
- Declare a temporary variable and initialize it with 0
- Find the last digit of the number
- Multiply the temporary variable by 10
- Add that last digit to the temporary variable
- Remove the last digit of the number.
- Repeat this process from 3 to 6 until the number becomes 0.

## How to Reverse a Number in Python

This python program using the **while loop** to reverse a number. We will take integer numbers while declaring the variables. Then, find the reverse of a number using the **while loop** and finally, the result will be displayed on the screen.

```
# Python program to reverse a number
# take inputs
num = int(input('Enter an integer number: '))
# calculate reverse of number
reverse = 0
while(num > 0):
last_digit = num % 10
reverse = reverse * 10 + last_digit
num = num // 10
# display result
print('The reverse number is = ', reverse)
```

Output for the different input values:-

Enter an integer number: 12345

The reverse number is = 54321

Enter an integer number: 35987642

The reverse number is = 24678953

## Reverse Integer using Recursion

We can also use the **recursion** technique to reverse a number in Python. A technique of defining the method/function that contains a call to itself is called recursion. The **recursive function/method** allows us to divide the complex problem into identical single simple cases that can handle easily. This is also a well-known computer programming technique: divide and conquer.

```
# Python program to reverse a number using recursion
reverse, base = 0, 1
def findReverse(num):
global reverse #function definition
global base #function definition
if(num > 0):
findReverse((int)(num/10))
reverse += (num % 10) * base
base *= 10
return reverse
# take inputs
num = int(input('Enter an integer number: '))
# display result
print('The reverse number is =', findReverse(num))
```

Output:-

Enter an integer number: 4987456

The reverse number is = 6547894

## Reverse a Number in Python using Slicing

We read a number and reverse a number using **slice operations**. We will convert the integer number to string using **str()** and then, calculate the reverse of a number using the **slicing operation**.

**Syntax of slicing operation:-** str(num) [::-1]

```
# Python program to reverse a number using slicing
# take inputs
num = int(input('Enter an integer number: '))
# calculate reverse of number
reverse = int(str(num)[::-1])
# display result
print('The reverse number is = ', reverse)
```

Output:-

Enter an integer number: 123456789

The reverse number is = 987654321

Also See:- Find Largest of 3 Numbers in Python

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