[Cody Dawg]

Okay, so here is a really cool math trick that a mathematics professor, a friend of mine, showed me up in Boston yesterday.

1. Grab a calculator or get ready to write this all out.

2. Key in the first THREE digits of your telephone number (BUT *NOT* THE AREA CODE)

3. Multiply by 80

4. Add 1

5. Multiply by 250

6. Add the last 4 digits of your telephone number (not one by one but ALL of the numbers in one big sum)

7. Add the last 4 digits of your telephone number again

8. Subtract 250

9. Divide number by 2

Do you recognize the number that is left?



If you have a good joke, also, post it will you?

Have a good day, everyone!

[Randman]

Cody Dawg + math tricks = +1

I hate math.

[Goldfinger]

Originally Posted by Cody Dawg

Do you recognize the number that is left?

Nope, probably doesn't work with my phone number.

My end result is 6580015 and my first 3 digits of my phonenumber are 658... Is that it ?

[Cody Dawg]

I think you're saying that because you can't add, Randman. Anyone who is semi-intelligent will get a big kick out of this. I'm even willing to bet that some of the members here are smart enough to know a few of their own and might add them to the thread.

Glad to see you're having a nice POSITIVE day again!

Take a math class will you? Basic addition, subtraction, division, and multiplication is all that is required here. Not linear algebra or calculus.

[Randman]

Originally Posted by Cody Dawg

Okay, so here is a really cool math trick that a mathematics professor, a friend of mine, showed me up in Boston yesterday.

1. Grab a calculator or get ready to write this all out.

2. Key in the first THREE digits of your telephone number (BUT *NOT* THE AREA CODE)

3. Multiply by 80

4. Add 1

5. Multiply by 250

6. Add the last 4 digits of your telephone number (not one by one but ALL of the numbers in one big sum)

7. Add the last 4 digits of your telephone number again

8. Subtract 250

9. Divide number by 2

Do you recognize the number that is left?

It didn't work. Missed an entire digit of my telephone number. And I tried it twice with a calculator.

Sorry Cody, joke's on you.

[Randman]

Originally Posted by Cody Dawg

I think you're saying that because you can't add, Randman.
Take a math class will you? Basic addition, subtraction, division, and multiplication is all that is required here. Not linear algebra or calculus.

Did I say I can't add? I can do math (inlcluding some upper-level stuff) just fine, I've just never enjoyed it. And I'm engaged to someone whose degree is mathematics. Just because someone doesn't like something, it doesn't mean that they can't do it.

You shouldn't be so judgmental.

[Cody Dawg]

randman said
It didn't work. Missed an entire digit of my telephone number. And I tried it twice with a calculator.

Sorry Cody, joke's on you.

randman, maybe you should take a math class. It works with every phone number we have.

In fact, here's the information number here in the United States (555-1212)

1. 555

2. x 80 = 44400

3. 44400 +1 = 44401

4. 44401 x 250 = 11100250

5. 11100250 + 1212 = 11101462

6. 11101462 + 1212 = 11102674

7. 11102674 - 250 = 11102424

8. 11102424 � 2 = 5551212

Someone give me a telephone number that it won't work with, will you?

[Mithras]

Incredible.

Who would think, that after multiplying (555) by 20,000 (i.e. 80 x 250), then adding (1212 x 2), throwing in an extraneous +250 - 250, and finally dividing by 2, one would get 5551212?

It boggles the mind.

[Cody Dawg]

goldfinger:

You gave us 658-0015

Here you go:

1. 658

2. 658 x 80 = 52640

3. 52640 + 1 = 52641

4. 52641 x 250 = 13160250

5. 13160250 + 0015 = 13160265

6. 13160250 + 0012 = 13160280

7. 13160280 - 250 = 13160030

8. 13160030 � 2 = 6580015

[Cody Dawg]

Mithras: You're great!

[Cody Dawg]

It's just a cool little trick or joke. (Hence, the thread.) If you have one you can add, please share it?

[Goldfinger]

Originally Posted by Cody Dawg

goldfinger:

You gave us 658-0015

Here you go:

1. 658

2. 658 x 80 = 52640

3. 52640 + 1 = 52641

4. 52641 x 250 = 13160250

5. 13160250 + 0015 = 13160265

6. 13160250 + 0012 = 13160280

7. 13160280 - 250 = 13160030

8. 13160030 � 2 = 6580015

Yeah, at the part where you need to add the last digits twice I made an error. I took the 4 last digits and added them to get 16 and I added that 16 instead of the 4 digit number. I redid it and it does indeed work out. A non-US phonenumer, but that probably doesn't matter too much.

[Weyland-Yutani]

Neat

Worked for me (European number and all)

[Ghoser777]

That's pretty basic to prove if you know some algebra.

[Cody Dawg]

It works for Europeans also?

Cool!

[SimpleLife]

Originally Posted by Cody Dawg

It works for Europeans also?

Cool!

It has nothing to do with nationality.

Certain terms are cancelling themselves out; the whole thing is that you provide the last 4 digits twice in the first place.

That trick would impress me far more if the 4 digits would "miraculously" appear without my input.

[Randman]

My telephone number has 8 digits. Does the trick work with 8-digits numbers?

[Weyland-Yutani]

Originally Posted by Randman

My telephone number has 8 digits. Does the trick work with 8-digits numbers?

No, at least not with these instructions.

[Mithras]

Originally Posted by Randman

My telephone number has 8 digits. Does the trick work with 8-digits numbers?

Here, I made a new one for ya (for EIGHT DIGITS ONLY, EUROPEAN AND SOME ASIAN TELEPHONE NUMBERS ONLY. May not work in Japan, Northern Cambodia, suburbs of Seoul, and Russia outside of Moscow):

1. Grab a calculator or get ready to write this all out.
2. Key in the first FOUR digits of your telephone number (BUT *NOT* THE AREA CODE)
3. Multiply by 125
4. Add 2
5. Multiply by 240
6. Add the last 4 digits of your telephone number (not one by one but ALL of the numbers in one big sum)
7. Add the last 4 digits of your telephone number again
8. Add the last 4 digits of your telephone number again
8. Subtract 480
9. Divide number by 3
Do you recognize the number that is left?

ASTONISHING!111111


I'm working towards my PhD in statistical learning theory, and I think I may use this as my final chapter, to really blow the socks off my committee.

[MaxPower2k3]

Originally Posted by Weyland-Yutani

No, at least not with these instructions.

it works just fine, just use the first four digits instead of the first three:

for 12345678:
1234 * 20,000 = 24680000
24680000 + 5678 + 5678 = 24691356
24691356 / 2 = 12345678

[Thorin]

UK numbers are 6 digits, so it doesn't work with those either (well, you get a 7 digit number out, with digits 3 and 4 being the same number).

[Cody Dawg]

Mithras:

You're way KEWL.



Love that!

Yes, it's sort of like building a house up piece by piece...then taking it back down piece by piece and people are amazed.

[MaxPower2k3]

Originally Posted by Thorin

UK numbers are 6 digits, so it doesn't work with those either (well, you get a 7 digit number out, with digits 3 and 4 being the same number).

in the first step, use the first two digits instead of the first three.

[Thorin]

Originally Posted by MaxPower2k3

it works just fine, just use the first four digits instead of the first three:

for 12345678:
1234 * 20,000 = 24680000
24680000 + 5678 + 5678 = 24691356
24691356 / 2 = 12345678

Yeah, it works for UK (6-digit) numbers if you just add the first 2 numbers to start with.

[Mithras]

Here's one in a similar vein:
You have to do this in your head, as you scroll down. Don't cheat!

1) pick a number from 1-9
2) subtract 5
3) multiply by 3

4) square the number (multiply by the same number -- not square root; and yes, you can square 0. It equals 0)
5) add the digits until you get only one digit (i.e. 64=6+4=10= 1+0=1)

6) if the number is less than 5, add five. Otherwise subtract 4.
7) multiply by 2
8) subtract 6

9) map the digit to a letter in the alphabet 1=A, 2=B, 3=C, etc...
10) pick a name of a European country that begins with that letter
11) take the second letter in the country name and think of a mammal that begins with that letter
12) think of the color of that mammal

13) Now highlight the following and compare: [ You have a gray elephant from Denmark (probably). ]

[Sealobo]

doesn't work for me... my phone # has 8 digits.

[Randman]

Originally Posted by Sealobo

doesn't work for me... my phone # has 8 digits.

That's because Cody assumes everyone is like her and has seven digits for a telephone number. I also like how she dissed my math skills right away,

Shame on you Cody. Shame on you.

[MaxPower2k3]

Mithras, mine was brown and had antlers, but same first letter so it still worked

[SimpleLife]

"Chocolate mathematics"

1. First of all, pick the number of times a week that you would like to have chocolate. (Try for more than once but less than 10.)

2. Multiply this number by 2 (Just to be bold)

3. Add 5. (for Sunday)

4. Multiply it by 50.

5. If you have already had your birthday this year add 1754. If you haven't, add 1753.

6. Now subtract the four digit year that you were born.

You should have a three digit number.

The first digit of this was your original number (i.e., how many times you want to have chocolate each week).

The next two numbers are:

Your age! (Oh yes, it is!!!!!)

This is the only year it will ever work, so spread it around while it last

[SimpleLife]

Here is a real one:

Marriage by Mathematics

People meet people, people marry people. When and how should someone decide to marry? Every time, John meets a suitable lady, he must make an important decision � to attempt to marry her or to move on to find a better mate. The problem is how does he know he will ever meet a better mate?

Lets do this mathematically. Suppose someone had 100 cards with 100 random numbers on them. He shows them to you one by one and you have to guess when you have seen the highest number in the whole pack (analogous to the best lady). The goal is to do it as soon as possible. You could wait till you have seen them all, then you will really find the largest number (in case of ladies, John has to wait his entire life to decide), but the sooner you make your move the better it is for you. Mathematicians have worked this out, and the best compromise is to pick the highest number after looking at 37 cards. That is about one third of your way into the game. Actually its not one third, but 1/e, where e is about 2.71828.

Suppose we assume the range of marriageable ages for women is about 18 to 40 and for men is about 20 to 45. Then a woman has 22 years to look for a mate, and a man has 25 years, but if a person waits too long, all the good ones will all be taken. Using the above strategy, the 1/e point for women is age 26.1 and for men is at age 29.1. Hence, this is the best time to take the plunge. The same theory, with a twist, can be used for arranged marriages. If you have gathered n prospects, make contact with the first random n/e prospects and then pick the best.

This technique is of course, quite useful in a variety of optimization problems.

[SimpleLife]

Here is a collection...

[MaxPower2k3]

Originally Posted by SimpleLife

"Chocolate mathematics"

it didn't work.

7 times per week

7*2 = 14
14 + 5 = 19
19 * 50 = 950
950 + 1753 = 2703
2703 - 715.

The 7 is right, but I'm 16, not 15

[skipjack]

Originally Posted by MaxPower2k3

it didn't work.

950 + 1753 = 2703
2703 - 715.

The 7 is right, but I'm 16, not 15

Those instructions were written for last year (1754 + 5*50).

[Ghoser777]

Originally Posted by SimpleLife

Here is a real one:

Best mathematical post in the thread.

[Ghoser777]

Let x be the first three digits of your telephone number
Let y be the last four digits of your telephone number

((x*80 + 1)*250 + 2*y - 250)/2

(x*20000 + 250 + 2*y - 250)/2

(x*20000 + 2*y)/2

x*10000 + y

So x*10000 + y ends up being the same as x0000 + y, and if y is only four digits long, then it's just xy (not x*y, the digits squished together).

To make it work for longer telephone numbers, here's a more general formula:

Let x be the first n digits of your telephone number
Let y be the remaining r digits of your telephone number
So n + r must be the number of digits in your telephone number
Let z be 10 raised to the r-3 power

((x*8*z + 1) * 250 + 2*y - 250)/2

So...

Key in the first n digits of your telephone number
Multiply by 8
Multiply by 10 as many times as their are remaining digits
Divide by 1000
Multiply by 250
Add the remaining digits (as a whole number, not an individual sum)
Add the remaining digits again
Subtract by 250
Divide by 2
Stare in awe

I believe this works, but I did it pretty quickly.

[Stradlater]

Originally Posted by Cody Dawg

Anyone who is semi-intelligent will get a big kick out of this.

Christ Almighty. Anyone who is semi-intelligent would know exactly how this "trick" works and be < mildly-amused.

Originally Posted by Mithras

Incredible.

Who would think, that after multiplying (555) by 20,000 (i.e. 80 x 250), then adding (1212 x 2), throwing in an extraneous +250 - 250, and finally dividing by 2, one would get 5551212?

It boggles the mind.

Now that's funny

[RangerJoe]

Originally Posted by Mithras

Here's one in a similar vein:
You have to do this in your head, as you scroll down. Don't cheat!

1) pick a number from 1-9
2) subtract 5
3) multiply by 3

4) square the number (multiply by the same number -- not square root; and yes, you can square 0. It equals 0)
5) add the digits until you get only one digit (i.e. 64=6+4=10= 1+0=1)

6) if the number is less than 5, add five. Otherwise subtract 4.
7) multiply by 2
8) subtract 6

9) map the digit to a letter in the alphabet 1=A, 2=B, 3=C, etc...
10) pick a name of a European country that begins with that letter
11) take the second letter in the country name and think of a mammal that begins with that letter
12) think of the color of that mammal

13) Now highlight the following and compare: [ You have a gray elephant from Denmark (probably). ]

That is soooo cool!

[entrox]

...

[Mithras]

Originally Posted by entrox

...

Oh, I think you caught your mistake just as I hit reply

[entrox]

Originally Posted by Mithras

Oh, I think you caught your mistake just as I hit reply

You're too fast. I thought I could sweep that embarrassing thing under the carpet

[SimpleLife]

Finally--a math trick for people who will follow directions!

Try this... it works!! Don't cheat by scrolling down or it
*won't* work!

STEP ONE:
Pick a number between 1 and 100.
Multiply it by 5.
Add your age minus the number in family.
Divide the number by 10 rounding to the nearest decimal.
Write down the number on one side of a piece of paper.

STEP TWO:
Pick another different number between 1 and 100.
Multiply by 1998.
Add the number in your family and subtract your age.
Divide the number by 10 rounding to the nearest decimal.
Write down the number on the other side of the piece of paper.

STEP THREE:
Take the first 2 digits of your home phone number and add them
to the last 2 digits of your work number and multiply by 365.
Write the number on a new sheet of paper.

STEP FOUR
Fold the first page in half.
Now fold the second page.
Place them side by side.
Now pick up the two sheets - sheet one in your left hand and
sheet two in your right hand.

NOW....





Find a bin/drawer and place the sheets in it....

Scroll down...






Now using both your hands...

Scroll down...






Slap yourself around the head while repeating:

"I'm a stupid person who wastes too much time on junk like
this."
Share This Joke With Your Friends

From here

With all due respect, the only trick is, as the quote presents, to have people follow orders/recipes/prescription and have them in awe. This is the sort of stuff illusionist do: "look at the light, then it disappear. Oh! I have your wallet!"

I am waiting for the one who'll prove a couple of mathematical conjounctures/hypotheses etc: like the Riemann Zeta function. That would be neat indeed. Or counting the infinities between Real Numbers.

Anyone crazy enough to tackle some Primes?

[chabig]

1. Write down the following "magic" number: 2005
2. Subtract the year of your birth.
3. Add 5
4. Subtract 10
5. Add 5 again and save this number for step 8
6. Write down the number of fingers a normal person has on one hand
7. Square this number (multiply it by itself)
8. Multiply this result by your answer from step 5
9. Divide by 25
10. Look into the future--how old will you be on December 31st?
11. Add this number to the year of your birth
12 Do you recognize this "magic" number?

Chris

[Amorya]

Originally Posted by Cody Dawg

Okay, so here is a really cool math trick that a mathematics professor, a friend of mine, showed me up in Boston yesterday.

My phone number is only six digits! Trick doesn't work

(I used to live in a house with a three digit phone number. Yey for rural areas!)

Originally Posted by Thorin

UK numbers are 6 digits, so it doesn't work with those either (well, you get a 7 digit number out, with digits 3 and 4 being the same number).

Some numbers are six digits. It depends on your area. New Mills (my exchange) has 6 digits. Buxton has 5. Manchester has 7.

Amorya

[Mithras]

I have discovered a truly remarkable result which this quick reply box is too small to contain.

[chabig]

Originally Posted by Mithras

I have discovered a truly remarkable result which this quick reply box is too small to contain.

Bravo!

[dcmacdaddy]

Originally Posted by Cody Dawg

goldfinger:

You gave us 658-0015

Here you go:

1. 658

2. 658 x 80 = 52640

3. 52640 + 1 = 52641

4. 52641 x 250 = 13160250

5. 13160250 + >>>0015<<< = 13160265

6. 13160250 + >>>0012<<< = 13160280

7. 13160280 - 250 = 13160030

8. 13160030 � 2 = 6580015

It works because your math is wrong. You are supposed to add the same sum twice.

[dcmacdaddy]

Originally Posted by Mithras

I have discovered a truly remarkable result which this quick reply box is too small to contain.

Good one!

Didn't the proof for Fermat's Last Theorem run to like 200 pages?

[Ghoser777]

Q: What's purple and commutes?
A: An Abelian Grape!

It took me till junior year in college in my math major to finally appreciate that joke =D

[SimpleLife]

Originally Posted by Mithras

I have discovered a truly remarkable result which this quick reply box is too small to contain.

Funny thing is that the darn proof almost did not make it.

x^n+y^n=z^n

where x, y, z, and n are integers, has no nonzero solutions for n > 2 has come to be known as Fermat's Last Theorem. It was called a "theorem" on the strength of Fermat's statement, despite the fact that no other mathematician was able to prove it for hundreds of years.

The proof of Fermat's Last Theorem marks the end of a mathematical era. Since virtually all of the tools which were eventually brought to bear on the problem had yet to be invented in the time of Fermat, it is interesting to speculate about whether he actually was in possession of an elementary proof of the theorem. Judging by the tenacity with which the problem resisted attack for so long, Fermat's alleged proof seems likely to have been illusionary. This conclusion is further supported by the fact that Fermat searched for proofs for the cases n = 4 and n = 5, which would have been superfluous had he actually been in possession of a general proof.

[ryaxnb]

Originally Posted by Cody Dawg

randman, maybe you should take a math class. It works with every phone number we have.

In fact, here's the information number here in the United States (555-1212)

1. 555

2. x 80 = 44400

3. 44400 +1 = 44401

4. 44401 x 250 = 11100250

5. 11100250 + 1212 = 11101462

6. 11101462 + 1212 = 11102674

7. 11102674 - 250 = 11102424

8. 11102424 � 2 = 5551212

Someone give me a telephone number that it won't work with, will you?

3350248