With question four we’re getting near the end of this series of Five Questions.

★★★★☆
Question 4: How many even prime numbers are there?
I’m not sure if this is a trick question, mathematically, or not.
First let’s be clear what a prime number actually is. It is a integer number which is divisible only by itself and 1. All even numbers (2, 4, 6, …) are divisible by 2. So 2 itself, is therefore the only even numbered prime number. And given that the technical definition of a prime number is that it has to be greater than 1, the answer is that there is just the one even prime. And there is no trick. (See Wikipedia for a fuller description.)
But why might this have been a trick question? Well I thought it might be a trick, because I did wonder about 0. Is 0 odd or even? Well actually it doesn’t matter because dividing 0 by anything you get 0, not 1, which seems to negate the question, regardless of the technical definition of a prime number.