test for even or odd

So I have come down to this, I am going to get a count of how many
elements there are of a certain tag. How can I test if the number is
even or odd? Stateing the obvious here but if it came back with 3 of
the tag I would want a "this number is odd" returned (or 1 and 0 for
even).

I already have my rows alternating in color, but there are two sets, I
need to first check for directories and place them and then I check
for files and place them. When I check for files I then check to see
if there was a even or odd number of files telling me what color to
start on!

Thanks!