How do you print numbers in reverse order in python while loop?

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

4321

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

  1. 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.
  2. After second iteration, digit equals 3, reversed equals 4 * 10 + 3 = 43 and num = 12.
  3. After third iteration, digit equals 2, reversed equals 43 * 10 + 2 = 432 and num = 1.
  4. After fourth iteration, digit equals 1, reversed equals 432 * 10 + 1 = 4321 and num = 0.
  5. 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

654321

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.

We will develop a program to reverse a number in python using while loop. To reverse a number we need to extract the last digit of the number and add that number into a temporary variable with some calculation, then remove the last digit of the number. Do these processes until the number becomes zero.

To remove the last digit the modulus operator [%] will be helpful for us, and to remove the last digit division operator [/] can be used. To add the last digit first we need to multiply the previous value by 10. Once you get the logic, you can write the program in any language.

Example of the reverse a number:-
Number: 56021
Reverse number: 12065

Procedure to find reverse of a number,

  1. Take a number
  2. Declare a temporary variable and initialize it with 0
  3. Find the last digit of the number
  4. Multiply the temporary variable by 10
  5. Add that last digit to the temporary variable
  6. Remove the last digit of the number.
  7. Repeat this process from 3 to 6 until the number becomes 0.

We will take integer numbers while declaring the variables. Then, find the reverse of a number using the while loop and finally, the result will be displayed on the screen.

# Python program to reverse a number using while loop

# take inputs
num = 12345

# calculate reverse of number
reverse = 0
while[num > 0]:
    last_digit = num % 10
    reverse = reverse * 10 + last_digit
    num = num // 10

# display result
print['The reverse number is =', reverse]

Output:-

The reverse number is = 54321

Reverse a Number in Python using While Loop

In the previous program, inputs are hardcoded in the program but in this program, input will be provided by the user.

# Python program to reverse a number using while loop

# take inputs
num = int[input['Enter a number: ']]

# calculate reverse of number
reverse = 0
while[num > 0]:
    last_digit = num % 10
    reverse = reverse * 10 + last_digit
    num = num // 10

# display result
print['The reverse number is =', reverse]

Output for the input values test-case-1:-

Enter a number: 416064
The reverse number is = 460614

Output for the input values test-case-2:-

Enter a number: 164532
The reverse number is = 235461

Python Program to Reverse a Number using While Loop

We can also take the help of a function to reverse a number in python using while loop. A function is a block of code that performs a specific task.

# Python program to reverse a number using while loop

def findReverse[n]:  #user-defined function
   # calculate reverse of number
   reverse = 0
   reminder = 0
   while[n != 0]:
      remainder = n % 10
      reverse = reverse * 10 + remainder
      n = int[n / 10]
   return reverse

# take inputs
num = int[input['Enter the number: ']]

# calling function and display result
reverse = findReverse[num]
print['The reverse number is =', reverse]

Output:-

Enter the number: 46894
The reverse number is = 49864

How do you print a reverse number in Python while loop?

Example 1: Reverse a Number using a while loop.
First, the remainder of the num divided by 10 is stored in the variable digit . ... .
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 ..

How do you reverse a number order in Python?

Reversing a number using reversed Method We use the python reversed[] function to reverse a number by this method. This function returns a pointer that can iterate the string/list in reverse order.

How do you reverse a number in a while loop?

C Program to reverse number using while loop.
#include .
int main[] {.
int num, rnum = 0, rem;.
printf["Enter any number: "];.
scanf["%d", &num];.
while [num != 0] {.
rem = num % 10;.
rnum = rnum * 10 + rem;.

How do you print numbers in reverse loop order?

C For Loop: Exercise-37 with Solution.
Pictorial Presentation:.
Sample Solution:.
C Code: #include 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:.

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