Question

Python 3

Calculate factorial

Create a function that uses a loop to calculate the factorial of a number.

* function name: get_fact
* parameters: num (int)
* returns: int
* operation:
Must use a loop here. Essentially calculate and return the factorial of
whatever number is provided.
but:
- If num is less than 1 or greater than 20, print "num is out of range"
and exit the function
- If num is not an int, print "invalid num parameter" and exit (easy way
to do this is to use exception handling around your range() function if you
use a for loop)
Recall that factorial of n is the product of all integers from 1 to n. For
example the factorial of 5 (5!) is 1*2*3*4*5 which is equal to 120. 4! is 24.
6! is 720. This will be extremely similar to the adding maching problem from
last time EXCEPT instead of adding a user-entered number each time, you are
instead multiplying by the next number in a sequence.
E.g.,
INITIALIZE PROD VARIABLE
LOOP X FROM 1 TO NUM
PROD GETS THE VALUE OF PROD TIMES X
RETURN PROD

Though of course you'll need a little more than that logic there to handle
the input validation.
* expected output:

>>> get_fact(5)
# RETURNS 120
>>> get_fact(6)
# RETURNS 720
>>> get_fact(21)
num is out of range
# RETURNS None
>>> get_fact('dude')
invalid num parameter
# RETURNS None
>>> get_fact(7.1)
invalid num parameter
# RETURNS None

Factorial of what: 6
6! is 720
Factorial of what: 25
num is out of range
Factorial of what: 0
Goodbye!

Answer 1

Code:

def get_int(num):
    if(num<1 or num>20):
        print("num is out of range")
        return None
    else:
        PROD=1;
        for x in range(1,num):
            PROD=PROD*x;
        return PROD
a=int(input("Factorial of what:"))
j=get_int(a);
if(j!=None):
    print(a,"! is ",j);

Output: