NINETY-NINE PERCENT.

This is an effect on page 134 of the book 'Magic With Cards' by Frank Garcia and George Schindler. I can not praise this book enough. It is the best of its kind.

The idea is that a deck of fify two cards (minus jokers) is throughly shuffled. The punter is then as asked to name any two card values. The bet is that cards showing these two values (e.g 6 and jack or whatever)will be present either next to one another-or at the very most-at only one card apart in the deck as the cards are dealt face up on the table.It is explained to the punter that the odds are very much in his favour since the chances of this happening must indeed be very small. To the punters surprise he loses the bet.This may be repeated and he will lose again and again.

Can anyone work out the mathematical odds of success in this endevour? The authors profess not to understand why it is the case that it always seems to work. I guess that we will be need to know-

1)The probability that the two values will exactly lie together somewhere in the deck.

Then by extention to this,

1)The probability that the two values will be either together or at most with just one card separating them as per the original bet.

I wish I was able enough in mathematics to do this myself but I have tried and failed.
Does it work 100%?

Many thanks Andy.

The probability of them being adjacent is 48.6 %. At most one card between them happens 73.6 % of the time. Far from 99 %, in other words. I've not calculated this, but simulated it 10 million times.

/Tomas

And, man is he tired.

/Tomas

Thanks Tomas, mere common sense suggested to me that it could not be anywhere near 100%.I admit however that I thought that it might be more than just 73.6%.Looks like the ruse has no potential then as a magical effect but interesting perhaps as a bet.

A further passing thought on this one.If we could find a means to increase the odds up from 48.6% to above 50% then the ruse would become more interesting for us. Say we were to use just the pip cards of the deck.That would mean 40 cards are in play rather than 52.The person could then be asked to name two different numerical values between one and ten. This may be enough to sway things significantly in our favor with respect to the bet of the two selected values being directly adjacent in the mix.

.....And then there is the deck of 25 ESP cards (5 symbols x5.) Although less impressive as a ruse,the probability of any two selected symbols ending up together will surely be highly to our advantage.

I do wish I had studied mathematics at school with more aptitude.

Plenty of cool things you can do with this. If you like to do card readings, then if the two cards end up next to each other, you do a reading on those. If there's one or two cards in between, those are the cards you use for a reading. If you're more magic inclined, if there ends up one card in between, you can always use an invisible deck. The key with this concept is that the participant doesn't know what to expect, so that allows you to do a little "jazz" with the result.

If you do it as suit next to value, your odds of success are much higher. As in:

"Think of a card, any card."
"The seven of spades."
"I had a feeling you would choose that. Look at this deck that has been here the whole time on the table. Last night I put a spade next to a seven. Look for yourself."

And so on. I'll leave the simulation to Tomas, but I'm guessing the probability of success is roughly (1-(9/16)^4) (I'm not accounting for the decrease in non-spade cards as you go along because I'm lazy, but I don't think that's going to throw things off too much). So that's around 90%. Do it with the same shuffled deck on three people, and you have about a 70% chance of hitting all three.

If your premise is that you pre-arranged the cards last night, then you can actually do so, and increase your chances to 100%

Yes absolutely correct.

So...

"Wilbur, Intuition is a funny thing. You mentioned the seven of spades as the first card that came to your mind. I asked you to shuffle the cards a moment before that. You had no conscious sense of how you were going to shuffle those cards. But subconsciously, you did an amazing thing. Look..."

Oooh...magic!





And then you quickly pull out your kazoo and play the entirety of Beethoven's Fifth to distract him from the fact that almost any card named would have had the same result.

There are a couple of nice things you can do with this; one is to talk about natural Blackjacks (A/ten value). Since you are starting with four Aces, and sixteen ten values, the odds are significantly higher than 46% (although I cannot remember the exact number off my head). If you want to see for yourselves, just shuffle and run through a few times. If you miss, I'll be very surprised!

Back in the 90s, on the EG, I posted a method for making this surefire, but it does rely on sleights. Basically, when you spot the first card that is not adjacent, you cull it under the spread. Keep track of this value, and if you see the other three before you get a match, or three of the other value without a match, you feed that card next to the final opposite value for a hit. I believe the misdirection I suggested at the time was 'comment casually that your leg is bleeding', but that might not work as well these days...

Finally, a story. In 1990 I was in flight school in Macon GA. Another of the students was called Zach Moinudhin, and his uncle was (I think) about third in the Pakistani government. Zach had been shipped over to the Deep South to learn how to be a pilot so he could, one day, take over the Pakistani airforce (I'm not kidding about that bit...). The problem was that Zach was not a natural pilot, and was booted from the school before too long. However, he did prefer to be baked out of his skull most of the time, and fly up to Atlantic City for the gambling. Several times I explained to him that casinos were money pits, but he didn't listen (or care). One day I told him that I was going to win a dollar from him and explained this bet (with two cards). He took the bet, and I won a dollar. I told him again that I would do the same thing; he bet and I won. I explained that I was _always_ going to win, but he kept betting and losing (about 12 dollars in total before I got bored. I should have played him for a hundred a shot - he would have gone for it...)

The moral? This hits far more than it misses, and some gamblers just won't listen...

Ian,love the Blackjack theme.A great application of the idea.