I’ve seen this interesting challange on Code Golf, and decided to compete. I’m losing miserably. I’ve managed to go as down as 65 byte in PHP, but i realised it won’t work, because i get the vars ($n, $k) from stdin. First, i don’t know how to work with stdin, second, that’d add up a nice bunch of bytes for my code (which is right now as follows)… Could someone tell me how stdin works and how could i make a 63 byte long code with that included?

<?=f($n)/f($n-$k)/f($k);function f($x){return $x>1?$x*f(--$x):1;}