Math Trick

September 29th, 2005 · 7 Comments · For Fun

Got this via e-mail …

Here is a math trick so unbelievable that it might 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?

Geez, why aren’t they running at least the financial part of the country?

Tags:

7 responses so far ↓

1 Matt // Sep 29, 2005 at 9:43 am

Thats just wierd!
2 Trelaina // Sep 29, 2005 at 2:05 pm

Okay, here comes the mathematics major to ruin it all

80×250 = 20,000, so any number that you multiply by 20,000 (which is essentially what you are doing) will be multipled by 2 and then have 4 zeroes added. That sets it up to look like your phone number, but have 0’s instead of the last four digits. You’ll of course add them in later!

The multiplication by 2 is just to make the whole thing cooler. I think (but don’t have time to prove right now) that you add 1 just before you multiply by 250 so that it works out when you eventually subtract out 250.

Then, you add the last four digits twice (so when you divide by 2 it comes out right).

Now subtract 250, which takes care of the 1 you added earlier.

Dividing by 2 gives you your number.

Sorry — just love seeing the math behind these….
3 Jo // Sep 29, 2005 at 2:09 pm

Hey — it still works and is cool
4 trelaina // Sep 29, 2005 at 6:09 pm

Oh, it’s definitely cool! Any math problem that triggers my interest enough to make me interrupt a steno-pad-page full of to-dos and work it out is a good one

…and I still have to figure out why the “add 1″ is in there!
5 oregano // Sep 29, 2005 at 10:16 pm

Math is cool? In as much as it helps me understand chemistry, which is truly cool… yeah, math is OK.
6 Stop The ACLU // Oct 2, 2005 at 12:17 am

Sunday Funnies

If you want to know more about me, send your questions to Basil. He will be interviewing me soon.
Happy Birthday Gribbit!!!
Steve The Pirate has the Carnival of Comedy
Rightwing Nuthouse has the Carnival of the Clueless
Outside The Beltway has th…
7 Stop The ACLU » Blog Archive » Sunday Funnies // Oct 2, 2005 at 12:27 am

[...] ng to spark some creativity Cafe Oregano has something priceless Jo’s Cafe has some fun with math My Vast Rightwing Conspiracy stirs the pot. Conservative Cat has his usual list of funny [...]