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The Magic Cafe Forum Index » » Magical equations » » Your Favorite Math Principle/Trick (1 Likes) Printer Friendly Version

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Hideo Kato
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Palindromic(al) Stack is same as Stay Stack and Mirror Stack.

Hideo Kato
Night_Crawler
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I like "Old wine in new bottles" I think it is pretty cool but I personally don't perform it cause it's a bit confusing to the spectator at first.

Night_Crawler
Hushai
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I posted a couple of things here a few days ago that were deleted by our Grammar Hostess by mistake, (Mya) and she asks that I repost them.

They were about Simon Aronson's "Undo Influence Control," which I would describe as a self-working, mathematical, non-sleight of hand card control that makes it possible to control two cards selected by two different spectators to virtually any two pre-selected positions in the deck.

That is, two spectators each get a genuinely free cut of the deck, they look at their cards, the magician reassembles the deck in what looks like a perfectly fair way, and the cards are then to be found at, say, the 18th and 43rd positions from the top of the deck, or wherever the magician has arranged to send them. Aronson gives a number of routines using the Undo Influence in his book "Try the Impossible."

He explains ways to do it that completely conceal the fact that it's all done by mathematics. It's amazing. It's a cliche, maybe, but you really do fool YOURSELF when you use the Undo Influence.
Scott Cram
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My favorite principle would have to be the binary principle, as employed in Leo Boudreau's books - "Spirited Pasteboards", "Skullduggery" and so on.

I've never seen a mathematical principle that can make tricks appear to be so close to mind reading. Leo's ingenuity in applying these principles really make the book.

The best application of this principle, in my mind, is his effect "Murder Most Foul". The spectator randomly selects, from a list of 64 possibilities, a murderer, a murder victim, a weapon, and a location. The spectator does this silently, and nothing is written down. Without so much as a single question, you instantly divine the exact murder scenario they have chosen.
MichelAsselin
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Scott, reads good have you ever performed it, seen it performed?
" , ? ; !!! "
- Marcel Marceau, Feb 30, 1945.
Scott Cram
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Performing "Murder Most Foul" was one of my proudest moments in my performing history. I've performed it many times for laypeople, and you can almost physically see that they're in another world for a few minutes.

There's one time where I performed it for a group of very knowledgeable magicians. My subject chose his scenario, and you could almost feel that every magician in the place was waiting for me to do something where I could obtain the needed information (write it down, etc.).

I slowly revealed the entire scenario, and it was like a domino effect. First, my subject's jaw fell open, and the rest, seeing that I got it right, were floored!

It's one thing to fool your fellow magicians, but this was different. They didn't even have a starting point to work with. They were just as much in unfamiliar territory as any of the laypeople I've performed for.
Rennie
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A good matematical trick I enjoy would have to be Miraskill by Stewart James. Though it does not use math in the sense of counting it is still based on mathmatics. Also the trick in the June 2003 Genii by Harry Lorayne called "Really" will have you scratching your head.
The effect is the important thing, how you achieve it is not.......
Larry Barnowsky
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When I was in 5th grade I discovered a book in the library on math tricks.
What intrigued me was the concept of
"casting out nines". I used it for years as a math check for multiplication. I wonder if anyone has used this as a force or prediction. For those not familiar with the concept here is an example:

45x23=1035 add the digits 4 and 5 and multiply by the sum of 2 and 3. You get 9x5=45, then 5+4=9 and 9 is equivalent to 0. You'll get the same number (0 in this case) if you add the digits in the product 1+0+3+5=9 or 0. Another example:

265x863=228695
2+6+5=13 and 1+3=4
8+6+3=17 and 1+7=8
Then 4x8=32 and 3+2=5

Add the digits in the product: 2+2+8+6+9+5=32 and 3+2=5 the same result.

You can shorten the calculations by equating any 9 with 0 and think of all the calculations as being done in mod 9 arithmatic.

If your spectator is not aware of this rule of casting out nines you could pull off some good magic. For example, you could force the #9 by giving the spectator a calculator and have him multiply a number you selected whose digit sum is 9 by any number of his choosing. You then have him add the digits until he has gotten down to a single digit and it will always wind up to be 9.
Hushai
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There's at least one "Nine Principle" trick using dimes and pennies in Jim Steinmeyer's book "Impuzzibilities." And, the venerable "Gray Elephant in Denmark" routine uses the Nine Principle, too. You find it all over the place. It's an old reliable.
-- Hushai
Nir Dahan
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I think Martin Gardner mentions in one of his books that the special characteristic that "9" has in our decimal system is only due to the fact that it is the last one digit number in the system. So the same would apply for "7" in an octal count, "F" (15) in a hexadecimal count and so on...
just a thought...
nir
Hushai
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In going through my books today I've found two more that give interesting suggestions for using the Nine Principle: "The Complete Idiot's Guide to Magic Tricks," by Tom Ogden, in the chapter he calls "Arithmetricks," and "Magic with Everyday Objects," by George Schindler, in the chapter on mentalism. I'm sure I've run across this fascinating principle in lots more books, too. I've figured that something like that observation by Martin Gardner that Nir mentions must be the case, but I've never been mathematician enough to be sure.
-- Hushai
Sid Mayer
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Think of any two digit number.
Subtract from it the sum of its two digits.
The result will always be a multiple of nine.
And, of course, the digital sum of any multiple of nine is nine.

Explanation, if needed, is:
Let A equal the first digit and B equal the second digit. Thus, the original two digit number is of the form 10A+B. Subtract the sum of the two digits (A+B) like so:
10A+B-(A+B)=9A.

This is arguably the simplest way to force a nine.

Sid
All the world's a stage ... and everybody on it is overacting.
Bill Hallahan
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The two digit case to force a nine is exploited in a number of simple tricks. The technique extends to more than two digits, and it doesn't matter if you combine the digits continuously. If you add the digits of any base 10 number, and subtract the resulting number from the original number, then you will get a multiple of 9! And of course, it's digits will sum down to 9. This is the principle of "casting out nines" that used to be used by accountants to check arithmetic before the advent of computers.

For example, staring with the number 1567,

1567

1 + 5 + 6 + 7 = 19

1567 - 19 = 1548 = 9 * 172

1 + 5 + 4 + 8 = 18 and 1 + 8 = 9

Also, you can repeatedly add the original digits down to fewer digits before subtracting, i.e.

1 + 5 + 6 + 7 = 19

1 + 9 = 10

1 + 0 = 1

1567 - 1 = 1566 = 9 * 174

You still get a multiple of 9, and of course those digits all add repeatedly until just 9 is obtained.

There is a lot more that can be written about this relating to sums, products, and quotients, but subtraction is always used in magic to get directly to a given result.
Most of the effects that use this "directly" are not strong, since many people realize that if you use a number on itself, then there can be some kind of cancellation leading to a predetermined result, even if they don't understand the relationship. I write "most" because there are some strong applications. A really cool application of this principle is The Flash Mind Reader. (Give this page time to load.)

By the way, this extends to other base systems, i.e. in base eight, you would cast out sevens. Of course, in the case of base two, the binary system, where you cast out twos, the result is trivial, and just reduces to parity, i.e. whether the number has an even or odd number of ones in it.
Humans make life so interesting. Do you know that in a universe so full of wonders, they have managed to create boredom. Quite astonishing.
- The character of ‘Death’ in the movie "Hogswatch"
Steven Steele
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I don't know the principle or the mathematics involved (I would love to know), but I do a trick with two stacks of six cards arranged in a palendromic order to each other. The two piles contain identical cards (for example each pile contains the Ace through 6 of Spades). Cards are dealt one at a time from the top to the bottom and the dealer is randomly told to switch piles as a word is spelled. At the end of the spelling, the top cards are shown to match. They are removed and another word is spelled one letter at a time, following the same procedure.

Anybody know why this works and any history associated with this principle?
Hushai
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A fun trick that works purely by probability (and thus belongs on this thread, I guess) can be found at http://magic.about.com/library/tricks/bltrick42a.htm

I first encountered this in Garcia & Schindler's "Magic with Cards." I present it as a sleight-of-hand trick I've been working on and haven't quite perfected, because I can get two cards of the same value together, but haven't been able to get them to be the same SUIT yet. I put the deck behind my back for a second and just riffle the cards, pretending to be instantly rearranging them, sight unseen, after the spectator has just shuffled them thoroughly. As I said, it's fun, and must be THE easiest magical effect anyone ever did. -- Hushai
dlhoyt
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Quote:
On 2003-06-17 00:47, Steven Steele wrote:
... I do a trick with two stacks of six cards arranged in a palendromic order to each other. ...
Anybody know why this works and any history associated with this principle?

Steven, this principle is explored in Max Maven's recent book, RedivideR (note the palindromic nature of the title). It is also the basis of an effect by Larry Becker -- Will the cards match, which can be found in Stunners, Plus. The Maven book has many effects that exploit the principle.

Dale Hoyt
Eric Rose
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My favorite math principle has to be the devilish little faro shuffle. My favorite faro based trick is Chaos by Pit Hartling. I love pattering about the precision necesary since its fully mathematical (entirely true) while chaotically placing cards and apparently mixing them horribly. Its a rare trick that makes an anti-faro entertaining.
highmagic
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I shall also mention the "Jackpot Coins", a simple mathematical effect illustrated by Gerard Croiset in the 18th century, and recently refurbished by Barrie Richardson in his "Theater of the Mind"
Brandon Harper
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I have been performing the following trick for quite some time. Many magicians are surprised to learn that this effect was created using a simple mathematical trick.

A deck of cards is shuffled and the spectator is asked to choose four cards, a free choice. You tell them that based on the cards chosen, the deck will reveal personal information about them. You turn the cards over and begin to reveal information about the spectator. Of course, you are completely wrong. You offer to try again, so you add enough cards to each chosen card to equal 10 (e.g. if the card is a six, you add four cards to that pile, if it is a Jack you don't add any). You then "read" these cards as well. Again, WRONG. You offer to try one more time. You add the values of the original four cards together and deal that many cards into a pile as well. You then tell the spectator that the next card is their lucky number. It is turned over and is a seven. You then deal the next seven cards face up and ask if they are relevant to the spectator. After a few seconds, the spectator will realize that the seven cards are their telephone number.
Scott Cram
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Quote:
On 2003-06-23 11:21, highmagic wrote:
I shall also mention the "Jackpot Coins", a simple mathematical effect illustrated by Gerard Croiset in the 18th century, and recently refurbished by Barrie Richardson in his "Theater of the Mind"


If you like Jackpot Coins, you'll love Stewart James' "Dollars and (Sixth) Sense", written up in Bob Farmer's Flim-Flam column in the February 1995 issue of MAGIC. Here's the effect as written in the column:

Quote:
Effect: Several coins and three bills, a one, a five and a ten are tabled. Four spectators, A, B, C and D, are watching.

You turn your back. Three spectators, A, B and C, divide the three bills among themselves, pocketing them.

You turn around and give one coin to A, two to B and three to C. Several coins are still left on the table.

Your turn your back and give the following instructions:

The person with the dollar is to take some more coins, as many coins as you gave him (he's doubling his coinage).

The person on holding the five is to take twice as many coins as you gave him.

The person holding the ten is to take four times as many coins as you gave him.

The fourth spectator, D, takes all the coins remaining on the table and conceals them in his fist.

You turn around and reveal the number of coins held by D. Then you name which person has the one, the five and the ten.


While I can't reveal the method, I can tell you where to find it. The way you reveal the number of coins D is holding is the same as used in "Jackpot Coins" (generically known as "Debit & Credit", BTW). The way you determine who has the 1, 5 and 10 is written up in Martin Gardner's "Encyclopedia of Impromptu Magic" under "Matches: Mathematical Tricks" (look at Item #10).

With those two clues, it shouldn't be hard to put the method together.
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