Echizento is spot on with this one. A rechenpfennig is a kind of jeton or token, typically used as a counter on a reckoning board, or as a "gambling chip" in games of chance. These were often made in Nuremberg, Germany.
This site is most excellent for identifying and dating these tokens.
Bonedigger posted a similar one in this thread.
Don't say "infinitely" when you mean "very"; otherwise, you'll have no word left when you want to talk about something really infinite. - C. S. Lewis