Hello, so recently my girlfriend spent a month in Florida visiting relatives. While she was there she stopped by Daytona Magic and picked me up a few cheap items. One of them was The Mystery Calculator.

6 cards, each bearing an arragnement of different ages. A spectator that you've never meet concentrates on their age or someone's age that they are close to. The spectator gives you back the cards that bear the age that he/she is concentrating on and you reveal it.

This is a trick that was in almost every single one of the magic sets my grandmother would give me on birthdays growing up. In fact, I even remember seeing this trick in Cracker Jack boxes, on the back of cereal boxes, etc.

This trick holds a certain nostalgia for me and I was just wondering, does anyone know anything about the origin of this effect?