. . . . . The Twenty-Card Mystery
I'll give you the preparation first; it requires considerable practice.
Then you can decide if you want to read any further.
Memorize these four words: ATLAS, BIBLE, GOOSE, THIGH.
You must imagine these words written in large letters on the table:
. . .
Note that each letter appears exactly twice in the arrangement.
. . There are two A's, two T's, two L's, and so on.
Now you must practice dealing ten pairs of cards on to this array.
Deal the first two cards onto the two A's.
Deal the first card onto the first "A", then locate the second "A" mentally.
. . (Think of the four words you memorized.)
Deal the next two cards onto the two T's.
The first "T" is easy; where is the other "T"?
. . It's the first letter of THIGH.
Deal the next two cards onto the two L's . . . and so on.
At first you will be dealing very slowly; you must stop and think of each letter
. . and locate the second location of that letter.
With some practice, you will be dealing faster and smoother.
The object is to appear to be placing the cards randomly on the table.
When you are fairly good at dealing the cards as described above,
. . try some variations.
Start, for example, with the two G's, then the two L's, etc.
When I deal the cards into the array, I get "sloppy".
The cards are not lined up neatly and they're slightly tipped.
After the dealing, I straighten them slightly, as if it doesn't matter.
Once you can deal the ten pairs smoothly without obvious pauses,
. . you are ready to perform a small miracle.
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You can have as many as ten volunteers for this trick.
Have someone shuffle the deck.
Take the deck and deal off ten pairs of cards,
. . tossing them randomly onto the table.
Have each volunteer choose any pair of cards and remember them.
Have them place the cards face down on the table.
Pick up the cards, a pair at a time, in any order, and make a single packet of cards.
. . (Use both hands and make it look as casual as possible.)
Now deal the twenty cards face up onto the ATLAS-BIBLE-GOOSE-THIGH array
. . as smoothly and randomly-appearing as possible.
As one of the volunteers "Which rows are your cards in?".
(You might sweep your hand from left to right to indicate the rows.)
When he tells you the rows, you can immediately tell him his two cards.
Suppose his says "The first and third rows" (or just points to them).
Imagine the words for these two rows: ATLAS and GOOSE.
What lettter appears twice? . . . the "S".
Point to the cards in the location of the S's.
Suppose the second volunteer says "Both in the second row."
The word is BIBLE . . . and there are two B's.
His cards are at those locations.
Continue in this manner for each of the volunteers.