Unbelievable math problem

[LegalAlien]

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.
Grab a calculator. (you won't be able to do this one in your Head)

1. Key in the first three digits of your phone number (NOT the Area code...)
2. Multiply by 80
3. Add 1
4. Multiply by 250
5. Add to this the last 4 digits of your phone number
6. Add to this the last 4 digits of your phone number again
7. Subtract 250
8. Divide number by 2

Do you recognize the answer ??

[REAPER]

What do you mean can't do it in your head?

I don't like to think at the best of times...YES I know that number, just can't figure out where from

[lazyerick]

hmmm rather interesting... and they aren't running the country because they are to busy sitting at a desk thinking up stuff like this

[leadsheep]

Actually, it's a pretty simple little formula. Anyone who knows their basic algebra could do this problem....

[LegalAlien]

Originally Posted by leadsheep

Actually, it's a pretty simple little formula. Anyone who knows their basic algebra could do this problem....

Mr. Sheep, please lead us in this one. Provide us with the formula and we can test our basic math skills.
(And welcome to the site.)

[leadsheep]

Hey, I've been out of town for a while. I wasn't ignoring your request. I'll walk you through it here. It's kinda tough without being able to do it in person, but we should be alright.

Okay....

Let's start by taking the numbers out of it. Let's make my phone number the following series of variables, since the digits could (essentially) be almost anything:

mnp.qrst <-- my new phone number.

Step 1: type in the first three digits. Let's suppose your digits are 275. Which actually means 2*100 + 7*10 + 5*1. My first three digits are: 100m + 10n + p.

Step 2: Multiply by 80
This will give me 80(100m +10n + p) which works out to 8000m + 800n + 80p

Step 3: Add 1
Roger that: 8000m + 800n + 80p +1

Step 4: Multiply by 250
250(8000m + 800n +80p +1) or 2,000,000m + 200,000n + 20,000p + 250

Step 5: Add to this the last 4 digits of your phone number.
Remember they aren't actually just "qrstv" they are 1000*q + 100*r ...
2,000,000m + 200,000n + 20,000p + 250 + 1000q + 100r + 10s + t

Step 6: Add to this the last 4 digits of your phone number again
Notice that this will make all of the digits multiplied by 2
2,000,000m + 200,000n + 20,000p + 250 + 2000q + 200r + 20s + 2t

Step 7: Subtract 250
Gladly! That gets rid of that pesky 250 that is interrupting everything!
2,000,000m + 200,000n + 20,000p + 2000q + 200r + 20s + 2t

Step 8: Divide number by 2
Perfect! This makes everything just the right number!
1,000,000m + 100,000n + 10,000p + 1000q + 100r + 10s + t

See how it works? It's the same for all of these things that get emailed around where it can "guess" your age or your birthday. It's just relying on a little bit of algebraic razzle-dazzle.

[LegalAlien]

Originally Posted by leadsheep

It's kinda tough without being able to do it in person, but we should be alright.

Thanks leadsheep, that worked just fine. I'm glad you came back to town .
What is your back ground if I may ask?

Bob.

[leadsheep]

Originally Posted by LegalAlien

Thanks leadsheep, that worked just fine. I'm glad you came back to town .
What is your back ground if I may ask?

Bob.

I'm a Math Teacher.... Ha!

[LegalAlien]

Originally Posted by leadsheep

I'm a Math Teacher.... Ha!

That's what I figured.
I'm a teacher too (Montessori, hence my signature), but at Elementary level. I haven't taught tho, since I emigrated to Canada in '96.

[leadsheep]

Originally Posted by LegalAlien

That's what I figured.
I'm a teacher too (Montessori, hence my signature), but at Elementary level. I haven't taught tho, since I emigrated to Canada in '96.

I wondered about that in your sig! I'm into my final bit of holidays, and then it's back to school...

I've considered a few times offering my services at an elementary level - essentially being the math expert for the school. I think that sometimes elementary students are subjected to math instruction by people who don't really love the subject - that's not right.