To declare, whether or not the spectator has given 13th turn to the die, put by you.

Props: a die, a sheet of paper, pen or pencil.

Adv. Pre: Remember, if a die is seen from such an angle that its three faces are visible simultaneously, then the sum of the dots on all its three faces can be either even or odd but when it is turned through a right angle then in this new position, looking at it from the same place and angle, the sum of the dots on the three faces which are now before you will always be different from what it was previously-odd will become even and even will become odd. Similarly, while the 13th turn is given it will change the original sum from odd to even and vice versa.

Ask a spectator to put the die on the sheet of paper and draw a square around it. Now add the dots of all three faces seen from this particular angle and see whether the number is odd or even?

Turn your back and ask the spectator to give 12 quarter-turns to the die in any of the 4 possible directions, mixing the direction of turns and now if he wishes, a 13th turn can also be given without telling you whether it is done or not.

Turn to look at the die from the same angle and count the dots. If the sum, differs from what it was previously, then the spectator has given it a 13th turn, otherwise not.