As you will know if you have been following the ebook adventures in The Casebook of Doctor Marcus Quigley, my character is an itinerant dentist, gambler and occasional bounty hunter. He is particularly fond of dice.
Most people are aware that on a die (that's the singular of dice) the numbers on two opposing faces add up to seven. This has been the basic design of dice since about 1400 BC. This little fact is used again and again in various dice tricks, such as the little effect I am going to describe here.
But less well known is the fact that dice can be right or left-handed. This is a topological principle in that right-handed and left-handed dice are mirror images of each other, which cannot be superimposed on each other.
Because the opposing numbers add up to seven, it means that the one, two and three and the six, five and four will meet at opposite vertices. Get a die in front of you and check that out.
Right and left-handed dice
Now place it in front of you so that the one is on top and so the two and the three are also visible. Western die will have the two on the left and the three will be to the right of it. That is, it goes counter-clockwise. This is called a right-handed die. It is the standard pattern of all western dice.
Chinese dice are left-handed. A left-handed die with the one on top will have the two on the right and the three on the left of it. That is, it is clockwise. You will see this on Mah Jong dice.
Look at the pips now. There are differences here also. Western dice tend to have all the pips either black or white. They are all the same colour and the same size.
Western and Eastern dice (Eastern in the centre)
AND NOW FOR DICE DIVINATION - an easy trick with three dice.
You hand a spectator three dice and get them to roll them while your back is turned. Then get them to make a stack of the three. You turn and with barely a look at the stack tell them that you can make a dice divination. You reveal a number, which will be the total of the numbers that are hidden from view.
As the top die is removed and the hidden numbers are added together, your audience will be amazed that you were correct.
The trick simply depends upon the principle that the two opposing faces always add up to 7. So when you turn you just glance at the top number. You then subtract that from 21 and you will have the total.
After giving the total you deliberately instruct the spectator on which number to add. Firstly, he should remove the top die and look at the number on its bottom. To this add the number of the second die that has been revealed. Then lift that up and add the number that was on its bottom, then the number on the top of the last die, and finally the number on the bottom of the last die.
This is as outlined in the Effect. The only thing to focus on is that you only glance at the top number, then you quickly look away. Misdirect the audience’s attention to the other numbers that are on the other faces, and the fact that you could not have seen them all.
That's it - Hey Presto!