It is the most asked programming question in the interview. We can reverse the integer number in Python using the different methods.
Here we will write the program which takes input number and reversed the same. Let’s understand the following methods of reversing the integer number.
 Using while loop
 Using recursion
Reverse a number using Python while loop
First, we understand the algorithm of this program. It will make easy to understand the program logic. Once you get the logic, you can write the program in any language, not only Python.
Algorithm
Input Integer: number
(1) Initialize variable revs_number = 0
(2) Loop while number > 0
(a) Multiply revs_number by 10 and add remainder of number
divide by 10 to revs_number
revs_number = revs_number*10 + number%10;
(b) Divide num by 10
(3) Return revs_number
Let’s implement the above algorithm in program.
Program
Ask for enter the number from the use
number = int(input("Enter the integer number: "))
Initiate value to null
revs_number = 0
reverse the integer number using the while loop
while (number > 0):
# Logic
remainder = number % 10
revs_number = (revs_number * 10) + remainder
number = number // 10Display the result
print(“The reverse number is : {}”.format(revs_number))
Output:
Enter the integer number: 12345
The reverse number is: 54321
Explanation 
Let’s understand this program step by step.
We initialed a number variable for user input and variable revs_number initial value to null.
First Iteration
Reminder = number %10
Reminder = 12345%10 = 5
Reverse = Reverse *10 + Reminder Initial value of revs_number is null
Reverse = 0 * 10 + 5 = 0 + 5 = 5
Number = Number //10
Number = 1234 //10 = 1234 // Now loop will iterate on this number.
Second Iteration
Now the number is 123, and the revs_number is 5. The while checks its condition and executes for the next iteration.
Reminder = Number % 10
Reminder = 1234 % 10 = 4
Reverse = Reverse *10+ Reminder = 5 * 10 + 4
Reverse = 50 + 4 = 54
Number = Number //10 = 12345 //10
Number = 123
Third Iteration
From the Second Iteration, the values of both Number and Reverse have been changed as: number = 123 and revs_number = 54
Reminder = Number %10
Reminder = 123%10 = 3
Reverse = Reverse *10+ Reminder = 54 * 10 + 3
Reverse = 540 + 3 = 543
Number = Number //10 = 123//10
Number = 12
How to reverse a number in Python
It is the most asked programming question in the interview. We can reverse the integer number in Python using the different methods.
Here we will write the program which takes input number and reversed the same. Let’s understand the following methods of reversing the integer number.
 Using while loop
 Using recursion
Reverse a number using Python while loop
First, we understand the algorithm of this program. It will make easy to understand the program logic. Once you get the logic, you can write the program in any language, not only Python.
Algorithm
 Input Integer: number
 (1) Initialize variable revs_number = 0
 (2) Loop while number > 0
 (a) Multiply revs_number by 10 and add remainder of number
 divide by 10 to revs_number
 revs_number = revs_number*10 + number%10;
 (b) Divide num by 10
 (3) Return revs_number
Let’s implement the above algorithm in program.
Program

Ask for enter the number from the use
 number = int(input("Enter the integer number: "))

Initiate value to null
 revs_number = 0

reverse the integer number using the while loop
 while (number > 0):

Logic
 remainder = number % 10
 revs_number = (revs_number * 10) + remainder
 number = number // 10

Display the result
 print(“The reverse number is : {}”.format(revs_number))
Output:
Enter the integer number: 12345 The reverse number is: 54321
Explanation 
Let’s understand this program step by step.
We initialed a number variable for user input and variable revs_number initial value to null.
First Iteration
Reminder = number %10
Reminder = 12345%10 = 5
Reverse = Reverse *10 + Reminder Initial value of revs_number is null
Reverse = 0 * 10 + 5 = 0 + 5 = 5
Number = Number //10
Number = 1234 //10 = 1234 // Now loop will iterate on this number.
Second Iteration
Now the number is 123, and the revs_number is 5. The while checks its condition and executes for the next iteration.
Reminder = Number % 10
Reminder = 1234 % 10 = 4
Reverse = Reverse *10+ Reminder = 5 * 10 + 4
Reverse = 50 + 4 = 54
Number = Number //10 = 12345 //10
Number = 123
Third Iteration
From the Second Iteration, the values of both Number and Reverse have been changed as: number = 123 and revs_number = 54
Reminder = Number %10
Reminder = 123%10 = 3
Reverse = Reverse *10+ Reminder = 54 * 10 + 3
Reverse = 540 + 3 = 543
Number = Number //10 = 123//10
Number = 12
Fourth Iteration
The modified number is 12 and the revs_number is 543: Now while executes again.
Reminder = Number %10
Reminder = 12 %10 = 2
Reverse = Reverse *10+ Reminder = 543 * 10 + 2
Reverse = 5430 + 2 = 5432
Number = Number //10 = 12//10
Number = 1
Fifth Iteration
Reminder = Number %10
Reminder = 1 %1 0 = 1
Reverse = Reverse *10+ Reminder = 5432 * 10 + 1
Reverse = 54320 + 1 = 54321
while loop is terminated because if found the false as a Boolean result.
You can enter the different number and check the result.
Reverse a Number Using Recursion
Let’s understand the following example.
num = int(input("Enter the number: "))
revr_num = 0 # initial value is 0. It will hold the reversed number
def recur_reverse(num):
global revr_num # We can use it out of the function
if (num > 0):
Reminder = num % 10
revr_num = (revr_num * 10) + Reminder
recur_reverse(num // 10)
return revr_num
revr_num = recur_reverse(num)
print("n Reverse of entered number is = %d" % revr_num)
How to reverse a number in Python
It is the most asked programming question in the interview. We can reverse the integer number in Python using the different methods.
Here we will write the program which takes input number and reversed the same. Let’s understand the following methods of reversing the integer number.
 Using while loop
 Using recursion
Reverse a number using Python while loop
First, we understand the algorithm of this program. It will make easy to understand the program logic. Once you get the logic, you can write the program in any language, not only Python.
Algorithm
 Input Integer: number
 (1) Initialize variable revs_number = 0
 (2) Loop while number > 0
 (a) Multiply revs_number by 10 and add remainder of number
 divide by 10 to revs_number
 revs_number = revs_number*10 + number%10;
 (b) Divide num by 10
 (3) Return revs_number
Let’s implement the above algorithm in program.
Program

Ask for enter the number from the use
 number = int(input("Enter the integer number: "))

Initiate value to null
 revs_number = 0

reverse the integer number using the while loop
 while (number > 0):

Logic
 remainder = number % 10
 revs_number = (revs_number * 10) + remainder
 number = number // 10

Display the result
 print(“The reverse number is : {}”.format(revs_number))
Output:
Enter the integer number: 12345 The reverse number is: 54321
Explanation 
Let’s understand this program step by step.
We initialed a number variable for user input and variable revs_number initial value to null.
First Iteration
Reminder = number %10
Reminder = 12345%10 = 5
Reverse = Reverse *10 + Reminder Initial value of revs_number is null
Reverse = 0 * 10 + 5 = 0 + 5 = 5
Number = Number //10
Number = 1234 //10 = 1234 // Now loop will iterate on this number.
Second Iteration
Now the number is 123, and the revs_number is 5. The while checks its condition and executes for the next iteration.
Reminder = Number % 10
Reminder = 1234 % 10 = 4
Reverse = Reverse *10+ Reminder = 5 * 10 + 4
Reverse = 50 + 4 = 54
Number = Number //10 = 12345 //10
Number = 123
Third Iteration
From the Second Iteration, the values of both Number and Reverse have been changed as: number = 123 and revs_number = 54
Reminder = Number %10
Reminder = 123%10 = 3
Reverse = Reverse *10+ Reminder = 54 * 10 + 3
Reverse = 540 + 3 = 543
Number = Number //10 = 123//10
Number = 12
Fourth Iteration
The modified number is 12 and the revs_number is 543: Now while executes again.
Reminder = Number %10
Reminder = 12 %10 = 2
Reverse = Reverse *10+ Reminder = 543 * 10 + 2
Reverse = 5430 + 2 = 5432
Number = Number //10 = 12//10
Number = 1
Fifth Iteration
Reminder = Number %10
Reminder = 1 %1 0 = 1
Reverse = Reverse *10+ Reminder = 5432 * 10 + 1
Reverse = 54320 + 1 = 54321
while loop is terminated because if found the false as a Boolean result.
You can enter the different number and check the result.
Reverse a Number Using Recursion
Let’s understand the following example.
num = int(input("Enter the number: ")) revr_num = 0 # initial value is 0. It will hold the reversed number def recur_reverse(num): global revr_num # We can use it out of the function if (num > 0): Reminder = num % 10 revr_num = (revr_num * 10) + Reminder recur_reverse(num // 10) return revr_num revr_num = recur_reverse(num) print("n Reverse of entered number is = %d" % revr_num)
Output:
Enter the number: 5426
The Reverse of entered number is = 6245
Logic is same in both programs. Once you understand the logic, it will easy to do it by own.