Code written under an event called Google Code-in.

factorial.py

# Method to calculate factorial of the number passed as a parameter using recursion.
def fact(num):
    if num <= 1:
        return 1
    return num * fact(num - 1) * 1.00

try:
    print('Enter a number: ') # Message to display on screen
    
    # I'm casting the entered string into float because if the entered number is 5.0 then it raises a ValueError,
    # which should not happen in this case. So, I'm using float()
    num = float(input()) 
    
    if num < 0: # Condition to check if the entered number is smaller than 0
        raise ValueError
        
    if num % 1 != 0: # Condition to check if the entered number have some decimal digits
        raise ValueError
        
    print(f'\nFactorial: {fact(num):.2f}') # Using f-string formatting to show 2 decimal places
    
except ValueError: 
    """
        This will handle situations when users have entered 
         - any string
         - any number smaller than 0
         - any number with decimal places.
    """
    print('\nOnly numbers greater than or equal to 0, with no decimal digits are accepted')