Execute this script:
<?
	$a = 250.02;
	$b = 210.10;
	$c =  39.92;

	echo "a = $a<br>\n";
	echo "b = $b<br>\n";
	echo "c = $c<br>\n";

	echo "(b+c)-a = " . (($b+$c)-$a) . "<br>\n";
?>

It SHOULD echo:
a = 250.02
b = 210.1
c = 39.92
(b+c)-a = 0

But it echoes on my machine:
a = 250.02
b = 210.1
c = 39.92
(b+c)-a = -2.8421709430404E-14

When you change the values, for example like this:
<?
	$a = 250.022;
	$b = 210.101;
	$c =  39.921;
?>
it echoes the correct values... if against all odds I am doing something wrong, please tell me....!

Marc, a very happy php programmer!


P.S. I compiled PHP with this command line:

'./configure' '--with-mysql' '--with-pgsql' '--with-esoob' '--with-magic-quotes' '--with-apxs' '--with-ftp' '--with-config-file-path=.'