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Topic: Card trick challenge 


An interesting mathematical principle. James challenges magicians to find a better way of dressing this up. https://www.youtube.com/watch?v=_Wv_qw3nQnI Mike 


Hello, This is really nice  thank you for posting the link! Well, let's start thinking... I see a disadvantage in the fact that it is presented as a prediction. In a prediction effect, the logical conclusion is that the result will be always the same (which is indeed the case). Instead, the first step could be to use a mag's choice to let the *spectator* select the right number among others. In the course of this selection process, we can even allow an absolute free choice between 16 and 25 (and work with either four cards or five cards). The next thing that leaves some room for improvements is that there is no convincing reason for taking the difference between card values. It would be nice to have a story such that: Each card shows the picture of a room in a mystical tower toghether with the information in which storey this room is located. Now we can ask how many storeys the knight/gnome/prisoner/... has to climb in order to go from the lower rooms to the other ones. It would be nice to see some other ideas. 


I'll throw in an idea that maybe someone can build on, to get away from cards. Specs each pick five ropes of differing length from a group of 10. They are arranged in size order and then paired. The magician demonstrates to the specs how to take a pair and snip off "the extra length" of the longer rope; he tosses the other two pieces away. The same is done for the other four pairs by the two specs. When the "extra lengths" are lined up, it is the exact length of another rope that has been stretched across the stage from the beginning. Yeah, it's a lousy payoff, but just wanted to show that the principle can be applied to something other than cards. 


Right, getting away from cards is the right thing. Another alternative could be to represent the numbers by stacks (e.g. of LEGO bricks). The number of bricks used to make everything the same level is known beforehand. 


Brilliant, saxonia. I love the Lego idea. And the payoff is a tower 25 bricks high hidden in a paper bag... 


Here's what I'd do ... I'd make two sets so I could repeat it with different results (I hope) I would use the Major Arcana .. 1 through 10 .. ( I'm assuming this also works with 11 to 20) Firstly I'd give them a sealed envelope .. "In this envelope is the psychic difference between you and I " ... I'd then produce a deck of tarot cards and bring the stacked ten to the top (Or just pull out 10) ..... I'd let them pick half of the cards without looking at ANY of them and I'd give them a five card reading on their selections and a quick reading on mine ... Then I'd ask what the difference there is between us ... Then I'd do the STANDARD NUMEROLOGICAL CALCULATIONS pointing out the numerical difference between his selections and mine ... It reduces to the number 7 .. a great Spiritual number...Then I'd let him walk away with the envelope ... The effect will finish itself without my help when he decides to open the envelope. 1 The Magician 2 The High Priestess 3 The Empress 4 The Emperor 5 The Hierophant 6 The Lovers 7 The Chariot 8 Justice 9 The Hermit 10 Wheel of Fortune And Hopefully the math works out for 11 to 20 .. Just guessing on my part .. So it could be repeated at least once ... :dancing: Is there a prize????????? :sun: The envelope would say 25 and describe the reduction techniques and what the other numbers also meant... 


Greetings, Since we're talking methods, I've taken my notions down to Inner Thoughts should you be interested. Scroll down the thread to my July 2, 2019 post: https://www.themagiccafe.com/forums/viewtopic.php?topic=694437&forum=82&118&start=100#17 Proizvolov's Identity is quite elegant, and is just begging for other applications! Thomas Henry 


Hello, In the meantime, another interesting thread was started in the inner section at: https://www.themagiccafe.com/forums/viewtopic.php?topic=696096&forum=82 Anyway, I prefer to continue the discussion in this thread because it reaches more people. I agree that we are discussing about a really nice method, but there is some danger that the method is stronger than the effect. I would appreciate if we could brainstorm about motivations for calculating the differences. Where do such differences naturally occur? Slim King's numerology plot with "The difference between us" is good  if one likes this kind of performance (which is not the case for me). But it is not easy to come up with a better reason for subtracting / correcting a difference. Maybe a plot could be about "missing / stolen money"? Any other ideas will be welcome! 


[quote]the method is stronger than the effect.[/quote] The problem, is, I think, that though initially intriguing, the method really doesn't stand up to very much scrutiny. Anyway, some more ideas: 1) Groups of socks. After selections, pair them up. Predict how many will be left over. 2) Trick that Fooled Einstein approach: "I'll have the same amount of money as you, plus $25 dollars will be left over for the two of us to spend." 3) Betting the total Over/Under score on a series of team sports events. 4) A dating service. Match pairs based on personalities. Predict how many people left over will need the special Miss Lonelyhearts service. 5) Ten beakers filled with different amounts of water, from 1 to ten ounces. Pair them up. Empty the smaller of the pair into a bucket. Pour the contents of the larger into the smaller, then throw that out too. Pour all the remaining water into a beaker that has a volume of exactly 25 ounces ... 6) Ten stopwatches set to ten different times from say 11 to 20 seconds. Pair them up. They start at the same time. When someone hears their partner's timer go off, s/he stops his or her own watch. The total time remaining on all watches will be 25 seconds. 


One more: "Taking the difference" naturally maps to driving a distance between two points. The cards refer to addresses in the same street, and we have to drive repeatedly from one house number to another one. Between house #3 and house #7, there are four units to drive, etc. We worry whether the amount of fuel in the car (or to be more modern: the battery power of our electric car) would be sufficient. Sounds like a good plot for using a Koornwinder Kar! I still have to think about what it would mean if the road is a circle instead of a straight line or if we also drive from the goal of one run to the starting point of the next one. I like landmark's idea of pairing and looking how many will be left over very much. This completely hides the subtraction. 


One little point about the pairing up process that might be helpful for some of the presentations: Imagine two identical racks or holders, each with space for five numbered items. Then the two specs can each set up their racks in the same way, numerically ascending from left to right, and they will be automatically paired correctly when the two holders are placed face to face. Which leads to a Scrabble theme. Ten face down Scrabble letter tiles. Five are chosen by each spec, arranged on their racks by the point count on the tile. The racks are put face to face, making up pairs. The difference in the tiles' pairs are then calculated matching a prediction. But I like saxonia's Lego idea and the Stop Watch idea as the most fun. To expand a little more on the stopwatch idea, Imagine inviting 11 people on stage. One of them is named the ref. The ref gets all 10 watches (each set to a different time), and hands out the watches to the other specs at random, according to his will. The ref then gets to divide the 10 players into two fiveplayer teams. Once the two teams are decided, the members even get a chance to make trades between the two teams as they wish. When all are satisfied, each team lines up in clock order, and then they pair off. The ref blows a whistle and each pair starts their stop watches. When a member of the team hears the other person's alarm, s/he stops his or her own watch. The ref then reads the times left over on all the watches, and then the predictionperhaps on a board which reads "Final Score"is revealed. It's still probably too much procedure for the strength of the reveal, but at least there would be a lot of opportunities for fun along the way. And I think it would be hard to backtrack or understand that there was a math principle involved. 


Respect! Everyone who is not afraid of ending in total chaos when performing the alarm clock version must be a performer with great audience management skills. I am glad that you like the LEGO idea, but I have to admit that I am not satisfied with my own idea until there is a really good story which gives reason for everything that has to be done. At least, LEGO towers would give a natural reason for sorting according to the increasing size: It would mean to build stairs. Just thinking... A logical reason for arranging money according to increasing amount could be that both spectators have racks where it is shown that the rightmost bag of money is secured by three locks and a watchdog (and security decreases from right to left). 