Is there a way to simulate a numeric keypad on apple wireless keyboard in OSX?
Macworld explained the procedure for a unibody MacBook, but I imagine the procedure is similar for an Apple wireless keyboard:

In order to bring the MacBook’s number pad functions back from the dead you need do nothing more than install [Edit: software is now called Karabiner-Elements] and restart your Mac. If you’re running Snow Leopard you don’t have to remap anything or even open the Preference Pane. Just hold down Fn plus the letters you mentioned and your laptop will cheerfully produce numbers as did your old one.

Link to Karabiner-Elements
Despite the name, this app will also work happily with non-MacBooks, or even non-Apple keyboards. I haven’t used it specifically to simulate a numeric keypad on an Apple wireless keyboard, but I have used it for other things and it generally works well.
It’s also well-maintained: the developer has been releasing regular bug fixes and new versions for OS X releases since late 2006.