## 16 September 2010

### I need some math help

Kev posted the photo above at Nothing To Do With Arbroath this morning.  It's obviously meant to be humorous, but it should be solvable.

To try to solve it, I assume that the first three - symbols are dashes, not subtraction signs, because she is trying to generate a telephone number.

The cube root of 54,872,000 is 380.

That gives 1-650-380-....

In the last figure, if the parenthesized number is 112, the result is of course negative (-12,535), and x7/10 comes to -8774.5.

Does she want it rounded off/up to yield 1-650-380-8775 ??   If so, why did she make it negative?  Or is the symbol before 7/10 actually a negative sign?

I think I need math help, and I don't want to call her.  So I'll blog it...

My take for the last grouping would be

7/10*(9-(11i)^2) =
7/10*(9-(11^2*i^2) =
And since i^2 = -1, the rest follows:
7/10*(9+11^2) =
7/10*130 = 91

but since four digits are required, I'd write it as 0091

So Paula's number is 1-650-380-0091

1. My take for the last grouping would be

7/10*(9-(11i)^2) =
7/10*(9-(11^2-i^2) =
7/10*(9+11^2) =
7/10*130 = 91

but since four digits are required, I'd write it as 0091

So Paula's number is 1-650-380-0091

2. Oops, I didn't proof that very well. The second line should be

7/10*(9-(11^2*i^2)

And since i^2 = -1, the rest follows.

3. Thank you, Anon! I misread the parenthesized part as the number 112. (I wouldn't have known what to do with an "i" anyway...)

Post amended. Want to append your name for credit and fame - without fortune?

4. My name's Steve Blunk, and I couldn't figure out how to go back and sign the posts. Imaginary numbers are, in this Chem E's opinion, a bizarre convenience for electrical engineers.

srb

5. although when you call that number, you don't get paula :( (not that I tried, because that would be creepy.)

6. I did worry about posting a wrong number (or any phone number), for fear that some innocent bystander would get plagued with calls.

Please no one call. It's just a math puzzle.

7. This same sign was posted 2 months ago on EPICWINFTW. There were 150 high quality responses, several interpretations and even one probably apocryphal romantic liaison claimed.

8. Pietr, that must have been the original source. Re the comment thread, I like the one here better - short and to the point.

9. Kudos to Steve Blunk. I only found the other blog by searching with his solution.