**Python reverse number: **Given a number, thee task is to reverse the given number in Python.

### Examples:

**Example1:**

**Input:**

number=12345

**Output:**

The reversed number = 54321

**Explanation:**

After reversing the number we get 54321

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**Example2:**

**Input:**

number=7341

**Output:**

The reversed number = 1437

**Example3:**

**Input:**

number=9840

**Output:**

The reversed number = 489

**Explanation:**

Here the reversed number is 0489 we neglect the leading zero so the reversed number is 489

## Reverse the given Number in Python

**Reverse a number python: **There are several ways to reverse the given number in python some of them are:

- Using while loop
- Using for loop and string concatenation
- Using Slicing
- Using list and join functions

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### Method #1:Using while loop

**Algorithm:**

- Scan the given number
- Set the variable reverse_number to 0.
- Loop while number > 0 Loop while number > 0
- Multiply reverse_number by 10 and add the remainder to reverse_number like below
- reverse_number = (reverse_number * 10) + remainder
- Divide the given number by 10 to remove the last digit.
- Print the reversed number

**Below is the implemenatation:**

# given number given_num = 12345 # Take a variable reverse_number and initialize it to null reverse_number = 0 # using while loop to reverse the given number while (given_num > 0): # implementing the algorithm # getting the last digit remainder = given_num % 10 reverse_number = (reverse_number * 10) + remainder given_num = given_num // 10 # Display the result print("The reversed number =", reverse_number)

**Output:**

The reversed number = 54321

### Method #2: Using for loop and string concatenation

**Approach: **

- Scan the given number.
- Take a empty string say
**revstring**. - Convert the given number to string using
**str()**function. - Traverse every character of the string using for loop in reverse order using range function.
- Add each character to
**revstring**using string concatenation. - Print the
**revstring.**

**Below is the implementation:**

**1)For numbers without trailing zeroes**

# given number given_num = 12345 # taking empty string reverse_string = "" # Convert the given_num to string using str strnum = str(given_num) # calculating the length of string length = len(strnum) # Traverse the strnum string in reverse order using for loop range function for index in range(length-1, -1, -1): # add the character to reverse_string using string concatenation reverse_string = reverse_string+strnum[index] # print the result print("The reversed number =", reverse_string)

**Output:**

The reversed number = 54321

**Note: **

Here it gives the correct result as their are no trailing zeroes

Let us consider a case where the given number contains trailing zeroes .

**EX: 9840**

**How to reverse a number in python: **The above algorithm gives the output

The reversed number = 0489

Here it also prints the leading zeroes so to avoid this the solution is given below.

**Solution:**

After getting the reversed string convert the string to integer using **int()** function which removes the leading zeroes

as below.

**2)For numbers with trailing zeroes**

# given number given_num = 9840 # taking empty string reverse_string = "" # Convert the given_num to string using str strnum = str(given_num) # calculating the length of string length = len(strnum) # Traverse the strnum string in reverse order using for loop range function for index in range(length-1, -1, -1): # add the character to reverse_string using string concatenation reverse_string = reverse_string+strnum[index] # converting the string to integer using int() function reverse_number = int(reverse_string) # print the result print("The reversed number =", reverse_number)

**Output:**

The reversed number = 489

### Method #3:Using Slicing

**Approach:**

- Scan the given number.
- Convert the given number to string using
**str()**function. - Reverse the string using slicing
- Convert this reversed string to integer to avoid leading zeros as mentioned in method #2.
- Print the reversed string.

**Below is the implementation:**

# given number given_num = 9840 # Convert the given_num to string using str strnum = str(given_num) # calculating the length of string length = len(strnum) # Reversing the string using slicing reverse_string = strnum[len(strnum)::-1] # converting the string to integer using int() function reverse_number = int(reverse_string) # print the result print("The reversed number =", reverse_number)

**Output:**

The reversed number = 489

### Method #4:Using list and join functions

**Approach:**

- Scan the given number.
- Convert the given number to string using
**str()**function. - Convert this string to list of digits using list() function.
- Reverse the list using reverse() function
- Join the list using join() function to get reversed string.
- Convert this reversed string to integer to avoid leading zeros as mentioned in method #2.
- Print the reversed string.

**Below is the implementation:**

# given number given_num = 9840 # Convert the given_num to string using str strnum = str(given_num) # converting to list of digits numberslist = list(strnum) # reverse the list and numberslist.reverse() # convert this list to string using join reverse_string = ''.join(numberslist) # converting the string to integer using int() function reverse_number = int(reverse_string) # print the result print("The reversed number =", reverse_number)

**Output:**

The reversed number = 489

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