Sum[x^2,{x,1,y}]-y*(y+1)*(2*y+1)/6
$ math
Mathematica 8.0 for Mac OS X x86 (64-bit)
Copyright 1988-2010 Wolfram Research, Inc.
In[1]:= Sum[x^2,{x,1,y}]-y*(y+1)*(2*y+1)/6
Out[1]= 0
Sum::iterb: Iterator does not have appropriate bounds.
Sum::iterb: Iterator does not have appropriate bounds.For comparison, similar software companies include MathWorks, the publishers of Matlab, with 2,400 employees and SAS Institute with 12,000 employees.
Totally made up numbers, but any chance I'm within a factor of 2? Posted only so somebody who knows what they're talking about can ridicule me with actually realistic numbers.
Mathematica development is split into two main groups. The Math Kernel group has about 20-30 engineers, and the FE group is around 10-15. There's a handfull of developers floating around that work on mathlink (a communication lib that allows external apps to hook into the math kernel).
Overall, they're actually a fairly efficient company. I can't speak to the current state of their finances, but I do know that about ten years ago (just after Methematica 5) they were running at about $24M gross anual revenue for the U.S, about $30M for asia, and $12M for U.K.