# Python Program to Reverse a Number

Write a program in python to reverse the digits of a number.

Example:
```Input: number = 1234
Output: reverse number = 4321
```

## Reverse a Number in Python

``````# Python program to reverse a number

def reverse(number):
reverse_number = 0

while(number>0):
r = number % 10;
reverse_number = reverse_number*10 + r
number = number / 10
return reverse_number;

# Driver Program

number = 1234

print("Given Number: ")
print(number)

print("Reversed Number: ")
print(reverse(number))``````

### Output:

```Given Number: 1234
Reversed Number: 4321
```

### Explanation:

We have defined a function reverse which takes one argument number. reverse_number variable is used to hold the reverse the number, initialized to 0. Now we get the last digit of original number by using modulo operation. We use the formula `reverse_number = reverse_number*10 + r` where r is the remainder i.e. the last digits of original number. Then divide the original number. Continue this process until original number becomes 0.

```Input: number = 1234

Pass this to reverse() function as reverse(number)

Set reverse number = 0

Get last digit r = 1234 % 10 = 4

reverse number = reverse number * 10 + r

So reverse number = 0 * 10 + 4 = 4

Divide original number by 10

number = number / 10

number = 1234 / 10 = 123

Again obtain as above, so r = 3
Again calculate reverse number as above, so
reverse number = 4 * 10 + 3 = 43
Again divide original number by 10, so
number = 12 (after dividing)

Again find r, r = 2
calculate reverse number = 43 * 10 + 2 = 432
Divide number by 10
So number = 1

Again find r, r = 1
calculate reverse number = 432 * 10 + 1 = 4321

Divide number by 10
So number = 1 / 10 = 0
So stop here and return the reverse number

Output: reverse number = 4321
```
You can also do this without using function, below is the code for that
``````# Python program to reverse a number

# set or accept number to reverse
number = 1234

# store original number
original_number = number

reverse_number = 0

while(number>0):
r = number % 10;
reverse_number = reverse_number*10 + r
number = number / 10

print("Given Number: ")
print(original_number)

print("Reversed Number: ")
print(reverse_number)``````