I have used the single ampersand (&) in C# to mean \"check the second conditional statement even if the first is false\".
But the
A single & is "Bitwise AND operator", just like dove said. I'm looking at second part of question: "why it works?"
Think in binary:
000 = 0
001 = 1
010 = 2
011 = 3
100 = 4
101 = 5
110 = 6
111 = 7
and so on
Note all even numbers ends with 0; so if last bit bitwise check against 1 returns zero (meaning "doesn't match"), its a even number;