really cool math trick

Kin'eleth · Post by **Kin'eleth** » Thu Jun 02, 2005 6:52 pm

try this. i dont know what the phone system for countries outside America is( meaning how many digits in a phone number), so if you dont live in the US than it might not work. anyway, try it.

Make sure you try this!!!!!

Here is a math trick so unbelievable that it will stump you.
Personally
I would like to know who came up with this and why that person is not running the country.
1. Grab a calculator. (you won't be able to do this one in your head)
2. Key in the first three digits of your phone number (NOT the area code)
3. Multiply by 80
4. Add 1
5. Multiply by 250
6. Add the last 4 digits of your phone number
7. Add the last 4 digits of your phone number again.
8. Subtract 250
9. Divide number by 2

Do you recognize the answer?

Lord k · Post by **Lord k** » Thu Jun 02, 2005 6:59 pm

well it didnt work for me. unsurprisingly as i live in the UK and so i only have a 6 digit phone number.

it really isnt that amazing though as all you are really doing is going round in circles.

for instance; adding one then multiplying by 250 then subtracting 250 is at least 2 too many steps

Pmpn8ez · Post by **Pmpn8ez** » Thu Jun 02, 2005 7:03 pm

Multiplication and subtraction are two very different operations; if it was multiplying and dividing, then I might see where it's just going in a circle. In essence, it is. However, using the same number to perform different operations (as long as they're not diametrically opposed) is relatively difficult to get back into sequence.

Kin'eleth · Post by **Kin'eleth** » Thu Jun 02, 2005 7:03 pm

yeah, US has 7 digit phone number. that without the 3 digit area code.

Asperon thorn · Post by **Asperon thorn** » Thu Jun 02, 2005 7:05 pm

Well if you simplify the expression, it isn't that neat.
x=Prefix
Y=Last 4

Code: Select all

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

(20,000x+250+2y)-250
--------------------------
                 2
20,000x+2y
-------------
      2

10,000x+y

Asperon Thorn

Malius · Post by **Malius** » Thu Jun 02, 2005 7:10 pm

well it didnt work for me. unsurprisingly as i live in the UK and so i only have a 6 digit phone number.

same

Well if you simplify the expression, it isn't that neat.
x=Prefix
Y=Last 4

code:

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

(20,000x+250+2y)-250
--------------------------
2
20,000x+2y
-------------
2

10,000x+y

Asperon Thorn

always good to see people who can actually be bothered to apply maths

Baranthazul · Post by **Baranthazul** » Thu Jun 02, 2005 7:14 pm

It worked for me. I saw something like this, where you picked a random number, and did something about your birthday, and you got your age. It was interesting.
---Baran

Asperon thorn · Post by **Asperon thorn** » Thu Jun 02, 2005 7:16 pm

If you live in the UK and have a 6 digit telephone #, change 80 to 8.

Asperon Thorn

Lord k · Post by **Lord k** » Thu Jun 02, 2005 7:23 pm

ye it works when using 8 .ta.

and pmpn my point was that the stages 4,5 and 8 all cancel down so that it is only the original number which is being multiplied by 250.

Pmpn8ez · Post by **Pmpn8ez** » Thu Jun 02, 2005 7:58 pm

I guess that's essentially all it is; a long series of steps that anyone who knows the math can easily break down using algebraic subsitutes. Oh well, c'est la vie, non?

Ilokir lúinwë · Post by **Ilokir lúinwë** » Thu Jun 02, 2005 8:57 pm

maths, I just keep wondering how you can avoid it in daily life...

next question: somebody knows the proof on Fermat by heart? :mrgreen:

Deathjester · Post by **Deathjester** » Thu Jun 02, 2005 9:58 pm

heh well if you think that, that's cool...

Step 1: -1/1 = 1/-1
Step 2: Taking the square root of both sides: sqrt(-1/1) = sqrt(1/-1)
Step 3: Simplifying: sqrt(-1)/sqrt(1) = sqrt(1)/sqrt(-1)
Step 4: In other words, i/1 = 1/i.
Step 5: Therefore, i / 2 = 1 / (2i),
Step 6: i/2 + 3/(2i) = 1/(2i) + 3/(2i),
Step 7: i (i/2 + 3/(2i) ) = i ( 1/(2i) + 3/(2i) ),
Step 8: (i^2)/2 + (3i)/(2i) = i/(21) + (3i)/(2i)
Step 9: (-1)/2 + 3/2 = 1/2 + 3/2,
Step 10: -(1/2) + 3/2 (1 and a half) = 1/2 + 3/2
Step 11: and this shows that 1=2.

so maths is pointless

Endalion · Post by **Endalion** » Thu Jun 02, 2005 10:19 pm

wow, who needs mathe these days

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

(20,000x+250+2y)-250
--------------------------
2
hate to break up the fun but it acctually is

20,000x+160xy+250+2y-250
---------------------------------
2

which means

20,000x+160xy+2y
----------------------
2
so

10,000x+80xy+y

is the real answer

Kin'eleth · Post by **Kin'eleth** » Thu Jun 02, 2005 11:50 pm

hmmmm?

Archdukechocula · Post by **Archdukechocula** » Fri Jun 03, 2005 1:20 am

Deathjester wrote:heh well if you think that, that's cool...

Step 1: -1/1 = 1/-1
Step 2: Taking the square root of both sides: sqrt(-1/1) = sqrt(1/-1)
Step 3: Simplifying: sqrt(-1)/sqrt(1) = sqrt(1)/sqrt(-1)
Step 4: In other words, i/1 = 1/i.
Step 5: Therefore, i / 2 = 1 / (2i),
Step 6: i/2 + 3/(2i) = 1/(2i) + 3/(2i),
Step 7: i (i/2 + 3/(2i) ) = i ( 1/(2i) + 3/(2i) ),
Step 8: (i^2)/2 + (3i)/(2i) = i/(21) + (3i)/(2i)
Step 9: (-1)/2 + 3/2 = 1/2 + 3/2,
Step 10: -(1/2) + 3/2 (1 and a half) = 1/2 + 3/2
Step 11: and this shows that 1=2.

so maths is pointless

It's a bit tricky to catch, but step 3 is wrong. The problem is that there is no rule that guarantees any given numbers square(a/b) is equivalent to (square a)/(square b), except when a and b are both positive. The proof does not meet that criteria, so the proof is fallacious.

Loflar · Post by **Loflar** » Fri Jun 03, 2005 4:28 am

And, sqrt(-1) may not be i. It could also be -i.

Lord doyok · Post by **Lord doyok** » Fri Jun 03, 2005 5:03 am

so maths is pointless

yeah.. that's why i hate math.. only times i'll be doing math is when i'm going to shops and when bulding my army list.

Asperon thorn · Post by **Asperon thorn** » Fri Jun 03, 2005 6:05 am

endalion wrote:wow, who needs mathe these days

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

(20,000x+250+2y)-250
--------------------------
2
hate to break up the fun but it acctually is

20,000x+160xy+250+2y-250
---------------------------------
2

which means

20,000x+160xy+2y
----------------------
2
so

10,000x+80xy+y

is the real answer

What? No it isn't. at no point are you multiplying and x term with a y term. to end up with xy. Check your order of operations again.

Asperon Thorn

Jazperdude · Post by **Jazperdude** » Fri Jun 03, 2005 6:40 am

don't you get that result from resolving the part between the ( ... ) ?

ahh so many years ago I was so good at math. Now I'm happy of I know 2+7

Nechra · Post by **Nechra** » Fri Jun 03, 2005 6:42 am

Also if you live in the uk, only add the last three digits of your fone number.

Loflar · Post by **Loflar** » Fri Jun 03, 2005 6:56 am

so maths is pointless

Only if you stick to integers ;-)

Lord Doyok wrote:yeah.. that's why i hate math.. only times i'll be doing math is when i'm going to shops and when bulding my army list.

That's not math, that's just counting ;-)

Deathjester · Post by **Deathjester** » Fri Jun 03, 2005 7:03 am

Archdukechocula wrote:It's a bit tricky to catch, but step 3 is wrong. The problem is that there is no rule that guarantees any given numbers square(a/b) is equivalent to (square a)/(square b), except when a and b are both positive. The proof does not meet that criteria, so the proof is fallacious.

thats right

but still it looks nice doesn't it

i could prove it by algebra as well, but again it's fallacious. it is in fact correct that 1 doesn't = 2

but as is correctly postulated, 1 and 2 are infact the same thing just viewed from a different set of perspectives.

Loflar · Post by **Loflar** » Fri Jun 03, 2005 7:07 am

Deathjester wrote:i could prove it by algebra as well, but again it's fallacious. it is in fact correct that 1 doesn't = 2

but as is correctly postulated, 1 and 2 are infact the same thing just viewed from a different set of perspectives.

You should also remember, that 1+1=3 for reasonably large values of 1 ;-)

Nechra · Post by **Nechra** » Fri Jun 03, 2005 7:15 am

Only for numbers as high as and lower than 1.49 recurring

Anaryin · Post by **Anaryin** » Fri Jun 03, 2005 12:13 pm

I knew that 90=100, but from a geometric point of view. Yet again, it's a fallacious trick, as if it was to be true, every number would be equal to another

Maths are nice if well explained. As for that Fermat stuff, I can't do it, but I can do Euler's equation.