I found it yesterday.

https://market.android.com/details?id=Tome.BookOfChances&feature=search_result#?t=W251bGwsMSwxLDEsIlRvbWUuQm9va09mQ2hhbmNlcyJd

If you have Android cellphone, this aplication calculate your chances to kill a monster, close a gate or anything else.

KoBe