Uhhh...that's probably the only constant you'll need to know, so, yeah.
.082 isn't hard to remember right? Just round it to .1 and take 10% of whatever n*T is (in PV=nRT) and divide it by either P or V to get what you want. Boom goes the dynamite!
I went in with tons of constants memorized and didn't use any, but hey, you might have to. #1 thing to learn is how to do problems really, really fast without actually writing anything down. Mental math and equation manipulation is your friend for the PCAT.