This is a very interesting little trick and always surprises people even though it is understood that it is worked on arithmetical principles. The performer turns his back and asks somebody to throw two dice onto the table. The performer then tells him what number he has thrown.
Procedure.
As soon as the dice have been thrown, the performer asks the person to take the uppermost number on either one of the dice and multiply it by two, then add 5 to the product and multiply the sum by 5, then add the uppermost number of the other dice.
When the performer is told the total figure, he at once announces the number of spots uppermost on each of the dice.
The performer has no complicated figuring to do. His only calculation is to subtract 25 from the last total given by the person who has thrown the dice. The remainder he obtains in this way will be a two-figure number.
One of these figures will indicate the number of spots uppermost on one of the dice, and the other figure will indicate the spots showing on the second dice.
obtained by the spectator was 60, the performer would subtract 25, obtaining a balance of 35. One of the dice would have 3 spots showing and the other dice 5 spots.