04 Mar, 2008

Here’s what we analytical type people do with their spare time: 

Today I received an e-mail with an “unbelievable math problem” in it.  It told me to “grab a calculator” because I wouldn’t be able to do it in my head.  Actually, if I had a piece of paper, a pencil, and a little bit of time, I wouldn’t need the calculator.  Here’s the text of the e-mail:

Here is a math trick so unbelievable that it will stump you. 

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? 

Okay, so let’s write it out and see what we get.  We’ll call the first three digits of your phone number “a” and the last four digits “b”.  So we’ve got:

(250(80a+1)+2b-250)/2 

Let’s clean that up by multiplying the 250 times the 80a+1…

(20000a+250+2b-250)/2 

Well, the +250 and the -250 cancel each other out, so:

(20000a+2b)/2 

And if we divide by 2…

10000a+b 

Since a = the first three digits of your phone number, (let’s say 555), 10000a would equal 5550000.  Remember, you just put the zeroes at the end and put your original number at the beginning or something like that.  Then when you add b, the last four digits of your phone number (say 9999), you get 5559999.

Yeah, I wasn’t stumped.  Mrs. Headley would be proud.