On: The Secret Number

[derleth]

> Why not have number systems where infinitesimals are allowed?

There are. A few of them, in fact. Look up the hyperreals.

[kalid → derleth]

Yep, exactly :). (Should have made it more clear that I was referring to other systems like surreals and hyperreals, but wasn't clear whether the parent was joking or not).

[Natsu → kalid]

I think you might like this:

http://www.cut-the-knot.org/WhatIs/Infinity/9999.shtml

[kalid → Natsu]

Thanks for the pointer! I enjoy discussions about .999... because it really makes us question what we mean about infinity (and assumptions about the reals).