print 1/2 # 0
print 1%2 # 1 <- remainder of the division
A better explanation:
The module operator, %, will bring back the remainder of a division between numbers, regardless if they're integers or float numbers.
While the slash operator, /, calling it this way since I have no idea what's the actual name of it, will bring the quotient of the division.
Q: So what's happening with my code is ...
A: Instead of checking if the reminder of a number by 3 is equal to zero, you're just checking the remainder of it.