Python program to reverse a given number (2 different ways)

1) Famous approach for reversing the number: Take input from the user and typecast into an integer, then iterate in the loop till num is not become zero, inside the loop:

• Find out the remainder.
• Using this: rev_num = rev_num * 10 + remainder.
• Update that number by diving by 10.
• After coming out of the loop printing the reverse number.

  if __name__ == "__main__" :
  
      # take string input from user
      num = int(input('Enter a number: '))
  
      rev_num = 0
  
      # iterate the loop till num is not equal to zero
      while(num) :
          rem = num % 10
          rev_num = rev_num* 10 + rem
          num //= 10
      
      print('Reverse number is: ', rev_num)

Output

Enter a number: 12345
Reverse number is:  54321

2) Make a user-defined function for reversing the Number: Take input from the user and typecast into integer, thenreverseNum() function call.

Inside the function:

• Iterate in the loop till num does not become zero:
• Find out the remainder.
• Using this: rev_num = rev_num * 10 + remainder.
• Update that number by diving by 10.
• After coming out of the loop returning the reverse number to the main.

  # define a function for finding 
  # reverse of the number
  def reverseNum(num) :
      
      rev_num = 0
  
      # iterate the loop till num is not equal to zero
      while(num) :
          rem = num % 10
          rev_num = rev_num* 10 + rem
          num //= 10
  
      return rev_num
  
  
  # Main() method
  if __name__ == "__main__" :
  
      # take string input from user
      num = int(input('Enter a number: '))
      
      print('Reverse number is: ', reverseNum(num))

Output

Enter a number: 12345
Reverse number is:  54321