{"id":3386,"date":"2019-08-01T15:17:43","date_gmt":"2019-08-01T15:17:43","guid":{"rendered":"https:\/\/robertjwallace.com\/?p=3386"},"modified":"2021-06-11T13:57:18","modified_gmt":"2021-06-11T13:57:18","slug":"mathematical-card-tricks","status":"publish","type":"post","link":"https:\/\/robertjwallace.com\/es\/mathematical-card-tricks\/","title":{"rendered":"Trucos matem\u00e1ticos con cartas"},"content":{"rendered":"

Me gustan los buenos trucos matem\u00e1ticos con cartas. Aunque suelen implicar mucho repartir cartas, pueden ser entretenidos, o al menos desconcertantes. Tengo un amigo matem\u00e1tico jubilado que imparti\u00f3 clases en la Universidad de Rutgers, y estos son algunos que me gustaba ense\u00f1arle. <\/p>\n\n\n\n\n\n\n\n

Building tens<\/h2>\n\n\n\n

The first two tricks use the same principal of “building tens”, but in different ways. For the first you have a card selected and then maneuver to the ninth card from the bottom of the deck. What I do is I spread the deck and have the spectator touch one. As I lift up the spread of cards with my right hand to show the spectator the card they touched, my left hand pushes four cards over to the right from the cards the left holds. Then as I place the right hand cards back I get a break under the four cards. <\/p>\n\n\n\n

I then cut to the break, dropping the cards cut to the table, and then cut twice more, dropping those cards on top of the cards to the table. At this point the selection is fifth from the bottom. <\/p>\n\n\n\n

Pick up the deck and do an out Faro. The cut does not have to be perfect. Only the bottom five cards of each half need to Faro. Now the selection is ninth from the bottom. <\/p>\n\n\n\n

Note that if you don’t want to use a Faro shuffle you can accomplish the same with an overhand shuffle. Run four cards, milk off at least five cards as you run the fifth and then shuffle off. Or you could also use a tabled riffle shuffle. When using a riffle shuffle I will split the deck in half with my right hand and as I do so I riffle four more cards with my right thumb and take a thumb break. Then when I begin the shuffle I drop the four cards from my right hand, then drop at least five from my left and then continue the shuffle normally. <\/p>\n\n\n\n

Okay, the selection is now position correctly, now explain you are going to find up to four cards using an “Algorithm”. You will deal cards face up, counting backwards aloud from ten. For example you deal the top card to the table, face up, and say “ten”. You deal the next card face up and say “nine”, and so on. You deal until the value of the card dealt matches the number you are counting. For example, assume the top cards are the following: 6d, 2s, 9d, 6h, As, Qs, 10c, and the 3d. Dealing the cards you would deal the 6d (ten), the 2s (nine) … 10c (four) and the 3d (three.) Since the 3d was dealt on the count of three you stop and place the 3d aside. <\/p>\n\n\n\n

Repeat the process again, starting the count from ten. If no cards match you will count all the way down to zero. Note that face cards are treated as tens. You will do this a total of four times after-which you will have set aside one, two, three or four cards. Take the cards you dealt, turn them face down and place them on the bottom of the deck.<\/p>\n\n\n\n

Explain that this Algorithm produced random cards from the deck and that these cards tell you where the spectators selection is located. Add the values of the cards and then use that number to deal to the selection.<\/p>\n\n\n\n

Building tens again<\/h2>\n\n\n\n

Using the same principal, this time as a prediction. Have the spectator shuffle the deck. You now have to determine the card at the 33rd position from the top. <\/p>\n\n\n\n

If you are proficient with Faro shuffles you should be able to split the deck in half, and spot the card at position 26. Then close up the deck and do an overhand shuffle, undercutting less that half of the deck. Run four cards, then three more, then six more. In-jog the next card and shuffle off. Undercut at the in-jog and run six cards and throw the rest of the deck on top. The card that was at position 26, that you spotted, is now at position 33.<\/p>\n\n\n\n

Alternatively, you can spread the deck face up to show them mixed. Spot the ninth card from the top of the deck. That will be your prediction. Do two out Faro shuffles to move that card to location 33.<\/p>\n\n\n\n

You can also spot the tenth card from the bottom and do an single in Faro shuffle. <\/p>\n\n\n\n

Now the deck is set. Write down your prediction. I then have the spectator choose one of the top four or five cards and remove the card and place it face up on the table. I explain the two more cards will be selected using the rule of ten. Starting with the value of the card face up on the table, deal face down onto the table counting from the value to ten. So if the card was a six, you would count, “seven, eight, nine, and ten” dealing four more cards. Turn the next card face up and repeat the deal\/count. Turn the next card face up and repeat the deal count. Drop the deck on the face down dealt cards.<\/p>\n\n\n\n

Add the values of the three face up cards and deal that many cards to the table. The last card dealt is turned face up to show it matches your prediction.<\/p>\n\n\n\n

You can see why this works if you imagine the first three cards are tens. In that case no cards are dealt face down. The tens add up to thirty, plus the three tens themselves makes 33.<\/p>\n\n\n\n

Stay Stack<\/h2>\n\n\n\n

The last trick uses the stay stack principal. Remove the Ace to five of hearts and place them in order from Ace to Five. Do the same with the Ace to five of spades.<\/p>\n\n\n\n

Drop one pile on top of the other and turn them face down. Have the spectator give the pile of ten cards a single cut and complete the cut. <\/p>\n\n\n\n

Now I do a series of false cuts. These look like they are mixing up the cards but in reality they are doing simple cuts.<\/p>\n\n\n\n

The first is simply pushing some cards from the top of the pile into the right hand with the left thumb. Then the left fingers push some cards from the bottom of the left hand cards and place them on top the the cards in the right hand. The left thumb pushes some more from the top and places them underneath the cards of the right hand. The remaining cards in the left hand puts them on top of the cards in the right hand. This simply cuts the cards.<\/p>\n\n\n\n

You can also hold the card in a right hand Biddle grip. Use the left thumb to pull off a block of cards (3 or 4) into the left hand. The left thumb comes back and pulls another block off, but keep a little finger break between the portions in the left hand. The right hand then comes over and as it covers the left hands cards, open the fingers of the left hand slightly. This causes the cards above the break to move to the right slightly. As the right hand deposits it cards on top of the left hand cards, the right ring finger and thumb grasp the side-jogged cards and pulls them out to the right, and then drops them on top. This is also simply a single cut.<\/p>\n\n\n\n

Hand the packet of ten cards to the spectator. Have them give the packet a single cut and complete the cut. Have them deal five cards, one at a time, into a pile on the table and then drop the remaining five into a pile next to the first five.<\/p>\n\n\n\n

At this point you tell the spectator that they are going to make all the decisions now. Tell them to transfer four cards, one at a time, from the top of either pile to the bottom of the same pile. Each card moved can be from either pile, so for example all four cards can be moved in the same pile, or a card can be moved from one pile and the next from the other, etc.<\/p>\n\n\n\n

After the cards have been moved remove the top cards from each pile and place them face down to the side.<\/p>\n\n\n\n

Have the spectator repeat the step of moving cards, but this time they move three instead of four. Take the top cards from each pile and place them face down to the side.<\/p>\n\n\n\n

Repeat with moving two cards instead of three. Take the top cards from each pile and place them face down to the side.<\/p>\n\n\n\n

Finally repeat with moving only one card. Take the top cards from each pile and place them face down to the side.<\/p>\n\n\n\n

Explain that this process of elimination arrive at two cards. Turn the last cards over to show that they match. Tell the spectator that that is an example of a coincidence. Turn the other four pairs of cards over showing that each one matches as you tell the spectator that that is an example of magic.<\/p>\n\n\n\n

Referencias<\/h2>\n\n\n\n