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Python program to reverse a given number (2 different ways)
Reversing a number in Python: Here, we are going to learn different ways to reverse a given number in Python.
Submitted by Ankit Rai, on July 28, 2019
Take input number from the user and print its reverse.
Example:
Input:
12345
Output:
54321
Here, we are implementing program to reversing a given number using 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
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