Oh, it does actually do multiplication! I didn't even know that.
So "1d20*10z" works as expected.
That's kind of cool.
Actually, a combined roller/calculator would probably not be much more difficult than a roller to implement, since order of operations and stuff is not very hard for a computer (it's all nicely defined and logical). However the MW dice-roller doesn't really work that way - "1d6+1d4" won't give you what you expect, for example. It instead treats a roll as XdY with some modifiers, which could include +N or *M or z or whatever, and lets you make several rolls, but it doesn't do any "proper" calculations stuff.