Pair or odd

How can we know if an integer number is pair or odd?
Of course, it is not too hard.
When I was just starting, I remembered I have looked for a way to do this, not too practical

floor($a / 2) == $a / 2;

The result is correct, but it can be much easier knowing the % operator

$a % 2 == 0;

However, you can still do it faster, but not necessarily easier, checking if the binary contains the 1 or not.

$a & 1 == 0

View example