The if statement isn't working correctly, and I don't know why [duplicate]

Question

The if statement isn't working! Write when I type in 4, the first part gets triggered even though this if statement part is false, because the number is 4, and not 1, 3, 5 or something.

Here's the entire code:

number = input("Choose number between 0 and 20 (you can use 0 and 20, too) ")
int(number)

if number == 1 or 3 or 5 or 7 or 9 or 11 or 13 or 15 or 17 or 19:
    number = int(number) * 3 + 1
    print(number)
elif number == 0 or 2 or 4 or 6 or 8 or 10 or 12 or 14 or 16 or 18 or 20:
    number = int(number) / 2
    print(number)
else:
    print("Run Code Again")

Answer 1

Your conditional statements need to be separated:

if number == 1 or number == 3 or number == 5, ... or number == 19:

It might be easier to use modulo to check for odd numbers:

if number % 2 == 1:

Answer 2

You are misusing the 'or' operator.

For instance:

print (1==2 or 3 or 5)

gives 3, not False.

print (1==(2 or 3 or 5))

would be closer to what you want, but this really just evaluates to 1==2 and would still be false even if 1 was in the or list as long as it wasn't the first non-zero item.

Answer 3

It is because conditions

3 or 5 or 7 or 9 or 11 or 13 or 15 or 17 or 19

is always true because you are not checking this with the number.

What you should do to make it logically correct is to compare them with your number like Martin's answer.