Self-Working Number Magic: 101 Foolproof Tricks

Self-Working Number Magic: 101 Foolproof Tricks

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by Karl Fulves, J. K. Schmidt

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Clear instructions for 101 tricks and problems, many based on important math principles. Calculations have been concealed; tricks are carefully streamlined for quick understanding and flawless performance. Master such number phenomena as Lightning Calculations, Giant Memory, Magic Squares, nearly 100 more. 98 illustrations.  See more details below


Clear instructions for 101 tricks and problems, many based on important math principles. Calculations have been concealed; tricks are carefully streamlined for quick understanding and flawless performance. Master such number phenomena as Lightning Calculations, Giant Memory, Magic Squares, nearly 100 more. 98 illustrations.

Product Details

Dover Publications
Publication date:
Dover Magic Books Series
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Product dimensions:
5.42(w) x 8.47(h) x 0.37(d)
Age Range:
10 Years

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By Karl Fulves, Joseph K. Schmidt

Dover Publications, Inc.

Copyright © 1983 Karl Fulves
All rights reserved.
ISBN: 978-0-486-15660-6



The tricks, stunts, and games described in this chapter provide clear plot ideas to the spectator. But although they are seemingly simple in effect, they lead to surprising conclusions. Although based on established principles, they are generally not well known, even to magicians, so they are likely to fool even the most sophisticated spectator.

No. 10 in this chapter is an excellent mystery called "Lightning Strikes Thrice." Based on Paul Swinford's description of a trick of Stewart Judah, it produces a baffling coincidence effect by means of ingenious subterfuge. Follow it with a trick like "Stunumbers" in the next chapter and you will have an exceptional combination.


"I just found something I had written in grade school," the magician says. He holds up the piece of paper shown in Figure 1. Written on it in script is "nine." The magician continues, "I remember it clearly. We were asked to write our age on a piece of paper. I wrote this number and handed in the paper. Too late I realized that I hadn't dotted the 'i.' The teacher had the paper so there was no way to correct the mistake."

The magician turns the paper over and places it writing-side down on the table.

Then he picks up another piece of paper and writes or draws the dot that's supposed to be on the "i." He says, "This was when I performed my first magic trick. I wrote a dot like this, then I erased it by magic." The magician rubs the paper and the dot mysteriously vanishes.

Picking up the "nine" paper, he turns it over. Now there is a dot over the "i," as shown in Figure 2. "Needless to say," he concludes, "I got an A + for my efforts. "

METHOD: This delightful trick is based on an idea of John Hamilton's. The secret is shown in Figure 3. The number nine is written in script in such a manner that it reads the same right side up or upside down. The dot is placed as shown.

When you hold the paper as in Figure 1 to display it, the right thumb covers the dot. Place the paper writing-side down on the table. Then pick up another piece of paper and pretend to draw a dot or circle. The spectators hear you write, but what they hear is the sound of the fingernail scraping against the paper.

Place the pencil aside. Pretend to cover the dot with the fingers. Rub the fingers back and forth. The dot seems to have vanished. Then pick up the "nine" paper, but make sure it is turned around so that the dot is uppermost. Now the number appears as shown in Figure 2. The dot has been magically transferred from one piece of paper to another.


Some computer dating systems use astrology and numerology to bring compatible people together. When you meet a happily married couple, offer to demonstrate how numerology applies to computer matching.

The husband and wife sit across the table from one another. Give each a piece of paper. Ask each to jot down a single-digit number, that is, any number from 1 to 9. You are standing or sitting at the husband's side of the table so you can't see his wife's number.

Ask her to do the computer figuring as follows. She is to double her number, add 2, multiply the result by 5, and subtract 3. Naturally the computer would do this instantly. When she has a result, ask her to hide it so you can't see it.

"The computer would have your number on file," the magician says to the wife. "And after doing that bit of figuring it would look for a compatible number in its memory bank. What result did you get?"

She might say 27. "You can see how well it works. You must be very compatible because you wrote a 2 and your husband wrote a 7." And they did!

METHOD: The puzzling aspect of this trick is that you never know the wife's number. It appears as if the result is completely random, yet the outcome is always a number that matches both the husband's and the wife's number.

The secret is that you have only to know the husband's number for the trick to work. Whatever digit he chose, subtract it from 10. In this example he wrote 7. Subtract it from 10 to get 3. In this case 3 is the key number.

Have the wife double her number, add 2, and multiply the result by 5. Then you have her subtract the key number, which in our example is 3. When she does, she will get back both of the original numbers.

To take the above example, she might write 2 and her husband 7. She would double 2 to get 4, add 2 to get 6, multiply the result by 5 to get 30, and subtract the key number 3 to get 27.

Remember that the key number is the result you get when you subtracts the husband's number from 10. It is not necessary to make it obvious that you know his number. You can glimpse it and then turn away. All that is required is a quick glimpse of the number for the work to be done.

As simple as this trick is, it has a strong effect. The happy couple will be delighted to discover that the computer verified their compatibility and they will be mystified as to how the computer knew.


"Some numbers refuse to be added," the magician says. "For example, if I ask you to write down the number 81, and under it I write the number 10, when these numbers are added they will not total 91."

The spectator is handed a pad and pencil. He writes the number 81, but he does so with the writing side of the pad away from him as shown in Figure 4. Then the magician takes the pad and under the spectator's number he writes 10. The pad is then given to someone else, who totals the numbers and arrives at the sum of 28. The arithmetic is correct, the numbers are not switched, there are no confederates, yet the total is different from the spectator's expectations.

The reason why is even more puzzling than the mysterious sum of 28 because the spectator discovers that although he definitely wrote 81, that is not what appears on the pad!

METHOD: The key to it is the manner of writing shown in Figure 4. When the spectator holds the pad as shown and writes the number 81 on the reverse side, the writing reverses itself, changing 81 to 18. You have only to try it once to convince yourself that it works.

To present the trick, draw a scribble on the pad, saying that it respresents a mysterious method of hypnotizing people into doing strange arithmetic. So that the spectator won't be influenced by this potent symbol, have him hold the pad with the back to him and jot down the number 81 on the other side.

Take the pad from him and under his number write the number 10. Draw a line below the two numbers and have someone total them. He will get 18 + 10 = 28. The first spectator will want to check the addition, but when he sees the writing he will be surprised to discover that his numbers have rearranged themselves. The hypnotic spell worked.


You offer the spectator an engagingly easy way to make a quick dollar. Deal 16 slips of paper or business cards in a row on the table. Show him that on half of the slips you have written, "I Owe You $1," and on the other slips you have written, "You Owe Me $1." The slips are writing-side down so no one can see the writing.

Tell the spectator to jot down the numbers 1, 2, 4, 8 on a pad in any order and to put plus and minus signs between the digits. He can use all plus signs or all minus signs or any combination of plus and minus signs. He might write the numbers like this:

4 2 8 1

And he might decide to use this combination of plus and minus signs:


You've explained beforehand that he's going to total the digits according to the indicated arithmetic operations, and further that he will disregard any negative sign that may show up in the answer, and finally that, whatever the result, he will count to that slip from his left. Remember that all this is explained beforehand so you cannot back out or change the rules.

In the above example he would perform the indicated addition and subtraction operations and arrive at the total of 13. He counts to the 13th slip, counting from left to right, and finds on it the words, "You Owe Me $1," meaning that he has just lost a dollar to you.

The game can be repeated any number of times. The spectator always loses.

METHOD: When you place the slips in a row, make sure the "You Owe Me $1" slips are in every odd position. The result is then automatic. You cannot lose because he must end up on an odd-numbered slip. If, for example, he arranges the slips in the order 2, 4, 1, 8, and puts in plus and minus signs as follows:


he will arrive at an answer of—3. As mentioned, he disregards the minus sign in the answer. He will thus arrive at the slip in the third position from the left and he loses.

You can cause the sum to be an even number by noting that the controlling factor is the digit 1. If you use just the digits 2, 4, 8, in any order, with any combination of plus and minus signs between them, the spectator must arrive at an even number.

To exploit this, write the numbers 1, 2, 4, 8, 16 on separate business cards or blank squares of cardboard. Lightly mark the back of the 1-card so you can recognize it at a glance.

Don't deal the 16 slips of paper in a row. Instead, arrange them in a packet so that the "I Owe You" slips alternate with the "You Owe Me" slips. The top slip of the packet is an "I Owe You" slip.

Hand the spectator the packet of five business cards. Tell him to mix them writing-side down and choose any three or four cards. Simply note whether or not he picks the 1-card. If he does, deal the 16 slips of paper from right to left. If he doesn't pick the 1-card, deal the groups of slips from left to right. Note that the real work is done before the game begins.

Have him arrange the chosen business cards in any order. Then tell him to place any combination of plus and minus signs between the numbers and carry out the arithmetic operations. Whatever the result, he counts to that number, beginning at the left. The word "left" indicates the left end of the row from the performer's view. This point should be made clear to the spectator at the start. You can simplify things by standing at the same side of the table as the spectator. In any event, when he counts to the chosen slip of paper, he will discover that he always ends up owing you money.


If you want to impress someone with a seemingly incredible talent for total recall, have him remove a dollar bill from his pocket and call out the digits of the serial number to you. Then tell him to circle one digit. After he does this, have him call out the remaining digits in any order. As soon as he does, you announce the digit he didn't call out!

METHOD: Oddly enough, if you tried to perform "Dollar-Bill Poker" by memorizing the digits, you would find it a difficult task. The reason is that the second time the spectator calls out the digits, he calls them out in any order. The trick can be done with memorization but there is a sneaky way to do the trick that is much easier.

When the spectator calls out the digits the first time, mentally add them together. Remember the total.

When he calls out the digits the second time he will call seven of the eight digits but will not call out the circled digit. Add the digits he calls out, then subtract this total from the previous total. The result is the circled number.

For example, say he calls out the serial number 48253176. As he calls out the digits, you mentally add them together as follows:


Remember the total of 36.

He might decide to circle the digit 3. Then he calls out the remaining digits in any order. When he does, mentally add them. The result may look like this:


Simply subtract the second total from the first, getting 36 - 33 = 3. Then announce that the circled digit is a 3.

The trick is simple but you should make it look difficult. When the spectator reads off the digits the first time, you can ask him to read them again. This may be necessary anyway if you didn't have a chance to add all digits, but it will make the trick appear more difficult. The throw-off is in your opening comments that you've been practicing memory tricks and can recall seven-digit and eight-digit numbers with ease. This seems like a logical explanation as to how you knew the circled digit, but even a memory expert will have trouble duplicating the trick if he tries to memorize the numbers.

Later in this book, in the chapter on Giant Memory, a system will be given that allows you to actually memorize an eight-digit number at a glance. The trick, called "Serial Secret" (No. 88), allows you to call out the memorized number forward or backward. After you have done "Serial Secret" you may want to switch to "Dollar-Bill Poker." It appears to be an even more impressive feat of memorization, but now you know that a fake method is used. Used together, the two tricks form a strong combination.


It is well known that each person has a twin, someone who looks the same, talks the same, and even thinks the same. The question is, where on the planet would one find his twin? By means of the International Telepathic Dialing System, one can locate the city where his twin lives.

The Telepathic Dialing System is shown in Figure 5. Place it before a spectator. Study him for a moment and then say, "I'm getting a mental picture of the city where your exact double can be found. He's on the same wavelength as you. In fact, right now he's using the Telepathic Dialing System to determine where his double lives. "

You jot down the word "Paris" on a piece of paper without anyone seeing it. Fold the paper and place it in a drinking glass or under a cup.

Now tell the spectator to take the last four digits of his home or business phone number and jot them down. Then have him jot down the same four digits in any scrambled order. Tell him to subtract the smaller number from the larger. Direct him then to add together all the digits in the total to arrive at a Telepathic Total.

Ask him to place his finger or the point of a pencil on Rome in the dial and count clockwise, with Rome as 1, Tokyo as 2, Athens as 3, and so on until he has advanced a number equal to his Telepathic Total. Surprisingly enough, he will arrive at Paris, exactly matching your prediction that his double lives in France.

METHOD: Make the circular dial of Figure 5 from cardboard. Nothing else is required. Proceed exactly as described above. If the spectator begins his count on Rome he will inevitably finish on Paris.

One example should make the procedure clear. Say that the last four digits in the spectator's phone number are 1284. He scrambles them and arrives at 8142. Subtracting the smaller number from the larger results in an answer of 6858. Adding together the digits in 6858, we arrive at 6 + 8 + 5 + 8 = 27. Begin at Rome, counting it as 1, then proceed clockwise 27 spaces. You will finish at Paris.

If someone else wants to try it, place the dial in front of him, but with some other city uppermost. Whatever city is at the top, the city he will end up on will be the one to the left of it in a counterclockwise direction. If, for example, he starts at New York, he will end at Madrid. Thus each spectator will discover his double in a different city.

The trick is puzzling because the spectator can choose any four-digit number. He thus reasons that you could not possibly know what number he will choose, nor how he will scramble the digits. This is true but it has no bearing on the outcome.

When doing the trick, be certain to use a four-digit number based on a telephone number. This is not necessary in a mathematical sense but it is important in terms of presentation. The telephone number ties in with the telephone dial and thus seems to be connected to it in some profound way. If you use any random four-digit number, the spectator will quickly conclude that the trick works on a mathematical premise. By making it appear that the spectator's phone number is crucial to the trick, you deepen the mystery.


Using a computer made of paper, you can beat an electronic machine if you know the secret. The paper calculator is shown in Figure 6. It consists of a folder with a window in it and a sliding piece with numbers on it. Place the sliding piece inside the folder as shown in Figure 7 and you have a machine that can beat the most sophisticated electronic calculator.

Have a spectator jot down a three-digit number and then repeat it to form a six-digit number. If he jotted down 638, he would repeat this number, arriving at 638,638.


Excerpted from SELF-WORKING NUMBER MAGIC by Karl Fulves, Joseph K. Schmidt. Copyright © 1983 Karl Fulves. Excerpted by permission of Dover Publications, Inc..
All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher.
Excerpts are provided by Dial-A-Book Inc. solely for the personal use of visitors to this web site.

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Meet the Author

Karl Fulves is one of the most respected authorities in the field of magic. For over 40 years, he has written hundreds of books on the subject and taught the art of illusion to thousands of people of all ages. This legendary figure also edited and published such magazines as Epilogue and The Pallbearers Review.

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