## Friday, July 17, 2009

### A Mathematician Goes on Vacation 6

I don't get too many complaints about the uselessness of negative numbers, but every once in a while in a Prealgebra class somebody will claim that they're never used in the real world. Above is the photographic evidence from within an elevator in Nikola Tesla Airport (Belgrade, Serbia) that negative integers are indeed used. And if one is ever in such an elevator, one surely thinks fondly (for once) of their math teacher. For how else would we know where to go?

**This is the last real post to this site. Next week yofx officially moves to a new home: www.yofx.org. This site will remain up as an archive for us to refer back to.

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## 3 comments:

I guess the minus sign in braille is the two adjacent horizontal dots that precede the number? I searched trying to confirm this but I couldn't find anything (if you find a link let me know).

Rick, yeah, that was tough. I had some pleasant detours though. I found a pdf from the Texas School of the Blind and Visually Impaired to confirm that the two preceding dots are a negative sign.

Cool, thanks. I don't think I would have found that (I didn't know that Braille for math is called "Nemeth Code").

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