http://www.perlmonks.org?node_id=1044135


in reply to A mod2 Machine.

using floats to compute modulo does not seem reasonable to me.
I only included this:
my $n = 534587; print "even\n" if($n % 2 == 0); # modulo operator of possibly a flo +at or possibly an integer (*)
because
  1. it is equivalent to the OP's "Most obvious (easiest) solution" (infact code-ninja used this exact example here: Re^2: A mod2 Machine.)
  2. it might actually be doing a (possibly comparatively slow) float operation because use integer was not used.
    It probably had to go: float 534587 --> integer 534587 --> integer modulo operation on integer 534587

Whereas doing a proper integer bit test should be faster:
use integer; my $n = 534587; print "even\n" if($n & 1 == 0); # checking LSB with Bitwise And on +an integer