This article discloses the Python Program to Reverse a Number using Python While Loop, Functions, and Recursion.
Python Program to Reverse a Number Using While Loop
This python program to reverse a number allows the user to enter any positive integer using a while loop. This program iterates each digit to inverse them.
Number = int(input("Please Enter any Number: ")) Reverse = 0 while(Number > 0): Reminder = Number %10 Reverse = (Reverse *10) + Reminder Number = Number //10 print("\n Reverse of entered number is = %d" %Reverse)
Please Enter any Number: 1456
Reverse of entered number is = 6541
This program allows the user to enter any positive integer. Then that number is assigned to a variable Number.
Next, Condition in the Python While loop makes sure that the given number is greater than 0.
From the above example, User Entered value: Number = 1456 and Reverse = 0
First Iteration
Reminder= Number%10
Reminder= 1456%10 = 6
Reverse= Reverse*10 + Reminder
Reverse= 0 * 10 + 6 = 0 + 6 = 6
Number= Number//10
Number= 1456 //10 = 145
Second Iteration
From the While Loop first Iteration, the values of both the Number and Reverse changed as Number= 145 and Reverse= 6
Reminder= Number% 10
Reminder= 145 % 10 = 5
Reverse= Reverse*10 + Reminder = 6 * 10 + 5
Reverse = 60 + 5 = 65
Number= 145 //10 = 14
Third Iteration
From the Second Iteration of Python reverse a Number program, Number= 14 and Reverse= 65
Reminder= 14%10 = 4
Reverse= 65 * 10 + 4 => 650 + 4 = 654
Number= 14//10 = 1
Fourth Iteration
From the third Iteration, Number = 1 and Reverse = 654
Reminder = 1 %10 = 1
Reverse= 654 * 10 + 1 => 6540 + 1 = 6541
Number= 1//10 = 0
Here, For the next iteration, Number= 0. So, the while loop condition fails.
Program to Reverse a Number Using Functions
This program to reverse a number in python allows the user to enter any positive integer. Then we are going to reverse a number using the Functions.
def rev_Integer(num): rev = 0 while(num > 0): rem = num %10 rev = (rev *10) + rem num = num //10 return rev num = int(input("Please Enter any Num: ")) rev = rev_Integer(num) print("\n Result = %d" %rev)
Please Enter any Num: 234589
Reverse = 985432
Within this program, When it reaches to rev = rev_Integer (num) line in the program then, the compiler immediately jumps to the below function:
def rev_Integer(Number):
The last line ends with a return Reverse statement.
Python Program to Reverse a Number using Recursion
This program to reverse a number allows the user to enter any positive integer. And then, we are going to reverse a number using Recursion.
rv = 0 def rv_Int(nm): global rv if(nm > 0): Reminder = nm %10 rv = (rv *10) + Reminder rv_Int(nm //10) return rv nm = int(input("Please Enter any Value : ")) rv = rv_Int(nm) print("\n The Result of entered is = %d" %rv)

In this example, When the compiler reaches to rv = rv_Int(nm) line in the program, then the compiler immediately jumps to the below function:
def rv_Int(nm):
In this function, the below statement helps to call the function Recursively with the updated value. If you miss this statement, it terminates after completing the first line.
Rerv_Int(nm //10)
For example, Number = 459 produces the output as 9
Let’s see the If Statement,
if (nm > 0), check whether the number is greater than 0 or not. For Recursive functions, placing a condition before using the function recursively is essential. Otherwise, we end up in infinite execution (Same as infinite Loop).
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