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Mental Magic: Surefire Tricks to Amaze Your Friends

Overview

A collection of math tricks using the magic of numbers in which the marvelous Professor Picanumber can seemingly predict random events in dozens of numerical exercises. Includes answers at the end.

A collection of math tricks using the magic of numbers in which the marvelous Professor Picanumba can seemingly predict random events in dozens of numerical exercises. Includes answers at the end.

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Overview

A collection of math tricks using the magic of numbers in which the marvelous Professor Picanumber can seemingly predict random events in dozens of numerical exercises. Includes answers at the end.

A collection of math tricks using the magic of numbers in which the marvelous Professor Picanumba can seemingly predict random events in dozens of numerical exercises. Includes answers at the end.

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Product Details

  • ISBN-13: 9780486474953
  • Publisher: Dover Publications
  • Publication date: 1/14/2010
  • Series: Dover Children's Activity Books Series
  • Pages: 96
  • Sales rank: 211,385
  • Age range: 8 years
  • Product dimensions: 5.50 (w) x 8.60 (h) x 0.50 (d)

Meet the Author


Martin Gardner was a renowned author who published over 70 books on subjects from science and math to poetry and religion. He also had a lifelong passion for magic tricks and puzzles. Well known for his mathematical games column in Scientific American and his "Trick of the Month" in Physics Teacher magazine, Gardner attracted a loyal following with his intelligence, wit, and imagination.

Martin Gardner: A Remembrance
The worldwide mathematical community was saddened by the death of Martin Gardner on May 22, 2010. Martin was 95 years old when he died, and had written 70 or 80 books during his long lifetime as an author. Martin's first Dover books were published in 1956 and 1957: Mathematics, Magic and Mystery, one of the first popular books on the intellectual excitement of mathematics to reach a wide audience, and Fads and Fallacies in the Name of Science, certainly one of the first popular books to cast a devastatingly skeptical eye on the claims of pseudoscience and the many guises in which the modern world has given rise to it. Both of these pioneering books are still in print with Dover today along with more than a dozen other titles of Martin's books. They run the gamut from his elementary Codes, Ciphers and Secret Writing, which has been enjoyed by generations of younger readers since the 1980s, to the more demanding The New Ambidextrous Universe: Symmetry and Asymmetry from Mirror Reflections to Superstrings, which Dover published in its final revised form in 2005.

To those of us who have been associated with Dover for a long time, however, Martin was more than an author, albeit a remarkably popular and successful one. As a member of the small group of long-time advisors and consultants, which included NYU's Morris Kline in mathematics, Harvard's I. Bernard Cohen in the history of science, and MIT's J. P. Den Hartog in engineering, Martin's advice and editorial suggestions in the formative 1950s helped to define the Dover publishing program and give it the point of view which — despite many changes, new directions, and the consequences of evolution — continues to be operative today.

In the Author's Own Words:
"Politicians, real-estate agents, used-car salesmen, and advertising copy-writers are expected to stretch facts in self-serving directions, but scientists who falsify their results are regarded by their peers as committing an inexcusable crime. Yet the sad fact is that the history of science swarms with cases of outright fakery and instances of scientists who unconsciously distorted their work by seeing it through lenses of passionately held beliefs."

"A surprising proportion of mathematicians are accomplished musicians. Is it because music and mathematics share patterns that are beautiful?" — Martin Gardner

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Read an Excerpt

Mental Magic

Surefire Tricks to Amaze Your Friends


By Martin Gardner, Jeff Sinclair

Dover Publications, Inc.

Copyright © 1999 Martin Gardner
All rights reserved.
ISBN: 978-0-486-14616-4



CHAPTER 1

The Tests


Wonderland Spell

Here is how Lewis Carroll began Alice in Wonderland:

Alice was beginning to get very tired of sitting by her sister on the bank, and of having nothing to do: once or twice she had peeped into the book her sister was reading.


Select any of the first 12 words. Starting on the next word, spell the word you chose, tapping a word for each letter. For example, If you selected the word "Alice" you spell A-L-I-C-E. Counting words for letters, this takes you to the word "very." So you spell V-E-R-Y, next ending on "by." Keep going. Note the word on which your spelling chain ends. What's the word?


A Mysterious Matrix

Make a copy of the 6-by-6 matrix on the page opposite.

Circle any number, then cross out all the numbers in the same row and the same column as the number you circled.

Select any number not crossed out and circle it. Again, cross out all numbers in the same row and same column as the circled number.

Repeat this four more times. There will be six circled numbers, each randomly chosen.

Add the six numbers. What's the total?


Cards that Shake Dice

In this exercise you use a deck of cards to simulate the tossing of a pair of dice.

Shuffle the cards, then start dealing them face up to form pile A. Stop as soon as a card turns up with a value of 1 through 6. This number represents the toss of one die.

As soon as you get a die number on pile A, start dealing a new pile B. Again, stop as soon as a card appears with a value of 1 through 6. This represents the toss of another die. Add the two numbers, and write the sum on a sheet of paper. The sum is as randomly obtained as if you had tossed a pair of dice.

After recording the results of the first "throw" of imaginary dice, shove the two piles aside and repeat the dealing into two more piles, to obtain a second dice "throw." Write the results of this second "throw" below the previous number.

Continue making "throws" in this manner until the entire deck has been used. Add all the "throws." Because each "throw" was as random as a toss of two dice, it seems impossible that Professor Picanumba could predict the sum of all the "throws."

What's the final sum?


Try This on a Dollar Bill

Write down the number on any dollar bill. Scramble the digits any way you like—that is, mix up their order. Jot down this second number.

Using your calculator, subtract the smaller number from the larger.

From the difference, take 7.

Copy the digits now on display, then add them all together. If the sum is more than one digit, add the digits once more. Keep adding the digits in the sums until just one digit is obtained.

What is it?


The Magic of 8

Multiply your phone number (disregard its area code) by 8. Write down the following three numbers:

1. Your phone number.

2. 8.

3. The product of your phone number and 8.


Add all the digits in those three numbers. If the sum is more than one digit, add again. Continue in this way until a single digit is reached.

What's the digit?


Around the Square

Toss a die on the table. Enter the number it shows into your calculator.

Multiply the number by 8.

Add 4.

Add the number on top of the die.

Now, on the grid below, put your finger on cell A and say "One." Tap clockwise around the square, tapping the cells as you go, and counting, 2, 3, 4, and so on. Stop tapping when you reach the number in your calculator's display.

On what letter did your finger end the count?


Nation, Animals, Fruit

Write down the following words:

1. The name of a nation that begins with D.

2. An animal that begins with the second letter of the nation.

3. The color of the animal.

4. An animal that begins with the last letter of the nation.

5. A fruit that begins with the last letter of the animal selected in step 4.


As a bonus, Professor Picanumba will tell you where you got those shoes you are wearing.


The Red and the Black

Shuffle a deck of cards, then deal 30 cards to the table to form a pile.

Count the number of black cards in the pile. From this number subtract the number of red cards in the rest of the deck. What's the difference?

Here's a quick question. If you add up all the digits in 1234567890 the sum is 45. If instead you multiply all the digits, will the product be more or less than 100?


The Exact Word

Think of any word on this page. Concentrate on it, then turn to the answer section. Believe it or not, the answer will print the exact word!


A Two-Dice Test

Toss a die. Think of a number from 1 through 6. Put another die on top of the one you tossed, turning it so the number you thought of is on top of the stack.

Carefully check the numbers on the two faces of the dice that are touching. Add those two numbers to the number you thought of, and write it down.

Think of another number from 1 through 6. Add it to the last result.

Remove the top die of the stack. Turn it so your second selected number is on top. Remove it from the stack and place it alongside the other die.

Lift up both dice. Add the sum of their bottom faces to your previous total.

What's your final sum?


A Curious Count

Shuffle a deck of cards, then start dealing them face up to form a pile. Say "Ten" when you deal the first card, "Nine" when you deal the second, "Eight" when you deal the third, and so on. In other words, as you deal you count backward from 10 to 1.

Assume that each face card (king, queen, or jack) has a value of 10.

As soon as you deal a card with a value that is the same as the number you say aloud, stop dealing and start a new pile. If you reach 10 without finding a match, "kill" the pile by putting a card face down on top of it.

Repeat this procedure until you have dealt four piles. If all four have been "killed," which is very unlikely, start the test all over again after another shuffle of the deck. After the four piles are finished, add the values of the cards at the top of each "living" pile. Call this sum "k".

Deal "k" cards from the remainder of the deck, then count the cards that remain.

How many are they?


A Rotating Matrix

Think a number from 1 through 16. Locate that number on the border of the matrix below. Turn the page so the number is at the top of the matrix.

Count the cells from left to right, top to bottom, starting the count on the top left corner cell. Note the symbol in the cell where the count ends.

What symbol is it?


Catch the Bill

Hold a dollar bill by one end as shown. Position your right hand so your thumb is on one side, fingers on the other, as if you were about to catch the bill when your left hand drops it. Your thumb and fingers must not touch the bill.

Let go of the bill with your left hand, and you will find that it is very easy to catch it in the other hand before the bill falls to the floor.

Now let someone else hold the bill while you try to catch it after it is dropped.

Can you catch the bill before it falls?


Five in a Row

Remove from a deck the nine of diamonds, the four of hearts, the queen of hearts, the ace of diamonds, and the seven of clubs.

Place the five cards face up in a row in the order shown here.

As you can see, there is one picture card, one ace, and one black card. Look them over carefully. Select one of the five cards and write it down.

Your choice is entirely free. What card did you write down?


Reverse, Subtract, Add

Write down any three-digit number provided no zero is used and that the first and last digits differ by more than 1.

Reverse the three digits to make a second number. For example, if you thought of 387 the reverse number would be 783.

Subtract the smaller number of the two from the larger. Reverse the result, then add it to the previous number.

Now translate the sum into a word by using the following chart:

[ILLUSTRATION OMITTED]

For each digit in the sum, substitute the letter at the top of the chart. What word do you get?


A Geometry Test

Draw a simple geometrical figure. Inside it draw another simple geometric figure.

What did you draw?


Monkey Business

If you had ten bananas and a monkey stole all but six how many bananas would you have left?


Face-Up Cards

Divide a deck into two halves of 26 cards each. Turn one half over so all its cards are face up. Shuffle them into the other half, which remains face down. Keep shuffling as long as you like, until you are satisfied the cards are thoroughly mixed.

Deal 26 cards to the table to form a pile. Put the rest of the deck down to make a second pile. Turn over either pile.

Count the number of face-up cards in each pile.

What is the difference between the two counts?


What's on the Paper?

Write any word you like on a sheet of paper. Fold the paper twice, then put it down and stand on it. Believe it or not, Professor Picanumba will tell you what is on the paper!

In addition, the professor will explain a method that enables you to see right through the walls of a house!


Count the Clips

Remove the contents of a small box of paper clips. Place exactly 20 clips in the box and set the rest of them aside.

Select a number fewer than ten. Take that number of clips out of the box and put them in your pocket.

Count the number of clips remaining in the box. Add the two digits of the count and remove that number of paper clips from the box. Put them in your pocket.

Take out three more paper clips.

How many clips are left in the box?


Number, Flower, Color

Think of a number between 10 and 50 that consists of two different digits, both of them odd. The numbers 11 and 33 are ruled out because their digits are alike. Write down the number you selected.

Under the number write the name of a flower.

Under the flower write a color. Most people think first of red, so don't pick red.

What are your three choices?


In Praise of Red

Red is the color of sunsets and fire,
And red is our blood when it flows.

A beautiful red are the lips of my love.
They rival the red of a rose.

We thrill to the red of a cardinal's wings,
But not to a sunburned red nose!

Roll one of your dice on the table.
Let "n" be the number it shows.


Look at the "n"th line of the poem above. Count to the "n"th word of that "n"th line.

What is the word?


Three Heaps

Form three heaps of paper clips in a row on the table. Each heap must contain the same number of clips and there must be more than three clips in each heap. (If paper clips are not handy, you can use beans, raisins, match sticks, toothpicks, or any other set of small objects.)

Take three clips from each end heap and put them on the middle heap. Count the number of clips in either end heap. Remove that number of clips from the center heap and place them on one of the end heaps.

Take a single clip from either end heap and put it in the middle heap.

How many clips are now in the middle heap?


Fold and Trim

Fold a sheet of paper in half four times, then unfold it. The creases will form a 4-by-4 matrix of cells as shown below.

[ILLUSTRATION OMITTED]

Number the cells from 1 through 16 as shown on the page opposite. Fold each crease forward and back a few times so the paper will fold easily either way along each crease.

Now fold the sheet into a packet the size of one cell. You can make the folds as tricky as you please, folding this way, that way—any way you like. You may even tuck folds between folds. In other words, make the folding as random as possible until you have a packet the size of a single cell.

With the scissors trim away all four edges of the folded paper packet so that it consists of sixteen separate pieces. Spread the pieces on the table. Some pieces will have their number-side up, others their number-side down. Add all the numbers on the face-up pieces. What is the sum?


Number Names

Think of any number from 1 through 100. Write down its name.

Count the number of letters in its name to obtain a second number.

Count the number of letters in the second number to obtain a third number.

Continue in this way until the chain of numbers ends on a number that keeps repeating.

What is this number?


A Test with Two Dice

Roll a pair of dice on the table. Call them A and B. Write down the following four different products:

1. The product of the top numbers on the dice.

2. The product of their bottom numbers.

3. The product of the top of A and the bottom of B.

4. The product of the top of B and the bottom of A.


Add the four products.

What is the sum?


Think-a-Letter

Select any one of the twenty-six letters of the alphabet. Look for your thought-of letter in each of the five columns below. Write down the letter at the top of each column in which your selected letter appears.

Change these letters to numbers, using the code A = 1, B = 2, C = 3, D = 4, and so on. Add the numbers that you obtain in this way.

Using the same code, turn the sum you get back into a letter. What letter does it yield?


Turn Two and Cut

Hold a packet of ten cards face down in your left hand. Turn the top pair of cards face up, then cut the packet at any spot you like. Again, turn the top two cards face up and cut. Keep up this turning a pair and cutting for as long as you like. This, of course, will randomize the positions of the face-up cards in the packet.

After you decide to stop reversing and cutting, deal the cards in a row on the table. Reverse all the cards at even positions along the row; that is, turn over the second, fourth, sixth, eighth, and tenth card.

How many cards in the row will now be face up?


The Rotated Die

Place a die on the square shape above so that you can see it's 1, 2, 3 faces, as shown on the right.

Give the die a quarter turn in any of two ways. You may rotate it clockwise or the other way, keeping it on the square, or you can tip it over an edge in any of the four directions, then slide it back onto the square. Each turn replaces one of the three visible faces by another face.

After you have made 13 random turns, add the three faces you now see. Is the sum odd or even.?


An ABCABC Number

Think of any three-digit number ABC. Enter it twice into your calculator as a six-digit number ABCABC.

Seven and 11 are lucky dice numbers, and 13 is considered an unlucky number.

Divide ABCABC by 7. Professor Picanumba predicts there will be no remainder. Sure enough, he's right!

Divide the result now on display by 11. The Professor again predicts correctly that there is no remainder.

Finally, divide the number on display by 13. Once more, there is no remainder.

What number is now showing on your calculator?


A Domino Chain

You need a complete set of 28 dominoes to do this test. Remove the one domino that has spots 2 and 5. Put it in your pocket.

Now pretend that you are playing a solitaire game of dominoes. Form the 27 pieces into one long single chain, placing them any way you like. When completed, note the number of spots at each end of the chain.

What are those two numbers?


The GRY Test

Think of a word that ends in GRY.

Professor Picanumba will tell you the word that you thought of. As a bonus, he'll tell you within four days the day you were born!

Now, how about a little riddle? A cowboy rode into Bottleneck on Friday, stayed three days, then rode out of town on Friday. How come?


Whisk the Dime

Hold your left hand palm up and put a dime on the center of the palm.

With a whisk broom in your other hand, try to brush the dime off your left hand.

Can you do it?


Here's another riddle. A barber in Chicago says he'd rather cut the hair of ten red- headed men than the hair of one brown-haired man. Can you guess why?


Beast, City, Vegetable

Write down words for the following:

1. A wild beast.

2. The largest city of a foreign country.

3. A vegetable.

What are the three words?


(Continues...)

Excerpted from Mental Magic by Martin Gardner, Jeff Sinclair. Copyright © 1999 Martin Gardner. 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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Table of Contents


The Tests
Wonderland Spell
A Mysterious Matrix
Cards that Shake Dice
Try This on a Dollar Bill
The Magic of 8
Around the Square
Nation, Animals, Fruit
The Red and the Black
The Exact Word
A Two-dice Test
A Curious Count
A Rotating Matrix
Catch the Bill
Five in a Row
Reverse, Subtract, Add
A Geometry Test
Monkey Business
Face-Up Cards
What's on the Paper?
Count the Clips
Number, Flower, Color
In Praise of Red
Three Heaps 
Fold and Trim
Number Names
A Test with Two Dice
Think-a-Letter
Turn Two and Cut
The Rotated Die
An ABCABC Number
A Domino chain
The GRY Test
Whisk the Dime
Beast, City, Vegetable
A Test with Your Age
A Surprising Sum
Around the Solar System
Think-a-Digit
A Remarkable Number
Heads or Tails?
Drop the Coin
At the Apex
A Calculator Test
A Peculiar Series
Rotating Spoon
Another Calculator Test
Four Queens
A Four-Dice Test
A Test with 66, 246, 913, 587
Funny Fractions
Topsy Turvy Fun
A Trick with Three Dice
Four Kings
Pairing Cards
Where's the Dime?
What's the Word?
Three Surprises
Another Calculator Surprise
A Surprising Fraction
Where's the Ace?
A Letter in Washington
Four File Cards
The Missing 8
An 8-Card Test
An Unexpected Number
Five Coins
The Stubborn Rubber Band
The Rotating Tubes
A Three-Dice Stack
One, Two, Three
Test of finger Strength
A 3 by 4 Test
The Curious Q
The Four Knights
Around the Circle
Deal and Switch
Insect, Animal, Bird
The Six Glasses
End of a Chain
A Yardstick Prediction
In Praise of Blue
Odd or Even?
Row of Nine
Nine-Card Spell
Lincoln Up or Down?
A Royal Finish
Twinkle, Twinkle
The Professor Predicts
Epilogue
About the Author
Index
 
 
 
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