How do you print a reverse number in for loop in python?

Question

Example 1: Reverse a Number using a while loop

num = 1234
reversed_num = 0

while num != 0:
    digit = num % 10
    reversed_num = reversed_num * 10 + digit
    num //= 10

print("Reversed Number: " + str(reversed_num))

Output

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Example 1: Reverse a Number using a while loop
Example 2: Using String slicing
Reverse a number using Python while loop
Reverse a Number Using Recursion
How do you reverse a value in Python?
How do you print numbers in reverse loop order?
How do you print a list in reverse order in for loop in Python?

In this program, while loop is used to reverse a number as given in the following steps:

First, the remainder of the num divided by 10 is stored in the variable digit. Now, the digit contains the last digit of num, i.e. 4.
digit is then added to the variable reversed after multiplying it by 10. Multiplication by 10 adds a new place in the reversed number. One-th place multiplied by 10 gives you tenth place, tenth gives you hundredth, and so on. In this case, reversed_num contains 0 * 10 + 4 = 4.
num is then divided by 10 so that now it only contains the first three digits: 123.
After second iteration, digit equals 3, reversed equals 4 * 10 + 3 = 43 and num = 12.
After third iteration, digit equals 2, reversed equals 43 * 10 + 2 = 432 and num = 1.
After fourth iteration, digit equals 1, reversed equals 432 * 10 + 1 = 4321 and num = 0.
Now num = 0, so the test expression num != 0 fails and while loop exits. reversed already contains the reversed number 4321.

Example 2: Using String slicing

num = 123456
print(str(num)[::-1])

Output

Using the string slicing concept, you can get reverse the string. ::-1 corresponds to start:stop:step. When you pass -1 as step, the start point goes to the end and stop at the front.

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

Let's implement the above algorithm in program.

Program

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.

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.

How do you reverse a value in Python?

Here is the source code of the Python Program to reverse a given number..

n=int(input("Enter number: ")) rev=0 while(n>0): dig=n%10 rev=rev*10+dig n=n//10 print("Reverse of the number:",rev).

Case 1: Enter number: 124 Reverse of the number: 421 Case 2: Enter number: 4538 Reverse of the number: 8354..

How do you print numbers in reverse loop order?

C For Loop: Exercise-37 with Solution.

Pictorial Presentation:.

Sample Solution:.

C Code: #include <stdio.h> void main(){ int num,r,sum=0,t; printf("Input a number: "); scanf("%d",&num); for(t=num;num!=0;num=num/10){ r=num % 10; sum=sum*10+r; } printf("The number in reverse order is : %d \n",sum); } ... .

Flowchart:.

How do you print a list in reverse order in for loop in Python?

3) Using for loop Another way to reverse python list without the use of any build-in methods is using loops. Create an empty list to copy the reversed elements. In the for loop, add the iterator as a list element at the beginning with the new list elements. So in that way, the list elements will be reversed.

programming python Reverse number Python