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GreatMathematicians BlaisePascal

LeonardoFibonacci

DavidHilbert

IsaacNewton

Archimedes

WhosNext???

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ArthurT.Benjamin BachelorofSciencefromCarnegieMellon

PhDfrom

Johns

Hopkins

ProfessoratHarveyMudd

Mathemagician

Presentationsaroundtheglobe

Advancedcalculations

Mathematicalagility

AmericasBestMathWhiz ReadersDigest

NottobeconfusedwithArthur Benjamin

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HisPresentationMentallymultiply

large

numbers

Mentallysquarefive

digitnumbers

MemorizePi

to

one

hundreddigits

MasterofPhonetic

Code

Andmore!

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Mathemagics

Mentalmath

Mathtricks:

Pickanumber

Whoa! Takeiteasy,makeit1or2digits

Doubleit

Add12

Divide

by

2

Subtractoriginalnumber

Isthenumber

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WhyEveryNumberAlwaysGoesTo6

Yournumberisx

Double

it:

2xThenadd12:2x+12

Thendivideby2:(2x+12)/2=x+6

Thensubtract

the

original

number:

x+6 x

=6

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Magical1089Pickathreedigitnumber(withthe

digitsdecreasing)

Reversenumber

Subtractreverse

fromoriginal

Callthisnewanswer:AnswerX

AddAnswer

X

to

the

reverseofAnswerX

Does it equal 1089?

If not, you made a mistake!

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WhyEveryNumberAlwaysGoesTo108abc = 3 digit number

This equals: 100a + 10b + c

cba = reverse of 3 digit numberThis equals 100c + 10b + a

Subtracting cba from abc equals:

(100a + 10b + c) (100c + 10b + a)

= 100(a - c) + (c a)

= 99(a-c)

We now receive one of the following multiples of 99:

198, 297, 396, 495, 594, 693, 792, 891

Adding the reverse of any of these numbers produces the answer 1089

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Multiplyingby11Twodigitnumber

Steps:Addthedigits

Placein

between

the

digits

Exceptiontotherule:

Ifsumisgreaterthan9

Addthe

digits

Placesecondnumberinbetweenthedigits

Addthe

1to

the

first

digit

of

the

new

number

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SquaringNumbersThatEndin5 Multiply first digit (or all digits but the last

one for three digit numbers or more) by nexthighest number

Place 25 at the end of new number Example: 25 x 25

2 x 3= 6

25 x 25= 625

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MemorizingDates Monday-1

Tuesday-2

Wednesday-3

Thursday-4

Friday-5

Saturday-6 Sunday-7 or 0

January-6*

February-2*

March-2

April-5

May-0

June-3

July-5

August-1

September-4

October-6

November-2

December-4

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YearCodesMemorizing Dates Continued 1900sadd1toyearcode

1800sadd3toyear

code

1700sand

2100s

add

5

toyearcode

2000+xx/4(ignoreremainder)

Add

new

number

to

xSubtractthenearestmultipleof7toreduce

(MonthCode+Date+YearCode)

nearestmultipleof7=

Day

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ArthurBenjamin

Mathemagician

http://www.math.hmc.edu/~benjamin/

http://www.youtube.com/watch?v=M4vqr3_ROIk

http://www.math.hmc.edu/~benjamin/http://www.youtube.com/watch?v=M4vqr3_ROIkhttp://www.youtube.com/watch?v=M4vqr3_ROIkhttp://www.math.hmc.edu/~benjamin/