(1 - (product (27-n)/(31-n), n=1 to 14)) * (1 - (product (29-n)/(31-n), n=2 to 15))

Uh oh! Wolfram|Alpha doesn't run without JavaScript.

Please enable JavaScript. If you don't know how, you can find instructionshere.Once you've done that, refresh this page to start using Wolfram|Alpha.