Well, duh. It is a computational engine, it's supposed to calculate well, right? It does seem obvious, but it's important to understand what this means from a practical standpoint. Not many users will type in complex mathematical formulas, but a lot of users need to know how much calories should they take daily, how to calculate their mortgage, and what's the distance between two cities. One way to think of Wolfram Alpha is as if someone collected all those various calculators scattered around the web and put them in one place. Google has been dabbling with this, adding currency conversion and other simple calculations to its search service, but WA is so vastly better than Google with this regard that you'll actually use it in your everyday life. And that means you won't have to visit obscure sites, usually designed in the last century, to find out what your body mass index is.