how come

[49er]

Phone number Calculator
Here is a math trick, can you figure the reason for the answer

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?

[P.C.]

That is SO excellent. I've tried to figure that one out before, with no luck.  It's a pretty cool trick.

[Marik]

WHAT?!?!? Nice trick!

[soapbox]

WTF?

 

could be a standard formula you have presented.this standard formula is applicable to all telephone directory systems????

[49er]

could be a standard formula you have presented.this standard formula is applicable to all telephone directory systems????

just playing with numbers really........

 

multiplying by 80, then 250.......is multiplying 20,000...the 4 zeros provide room for the last 4 digits of the phone number....this large number is divided by two which in effect the original 3 digits were multiplied by 10,000

 

adding 1....multiplying by 250 = 250....which is deducted off in step 8

 

the last 4 digits are added twice and divided by 2 = last 4 digits

 

am I making sense?

[soapbox]

yup.

[P.C.]

49er....am I making sense?

 

You could be.  I'm certain I wouldn't recognize it if you were.  I'm just going to stick with "Geee, what a neat trick".