This works for a lot of stuff. If you are only giving one input it'll work. So things like "\sin x", "x^2" \frac12" work. Interestingly you need a space in the sin example but not in the others. But "x^12" is the same as "x^{1} 2". So be careful with the shortcut.
I remember being surprised when I first saw \frac12, and I was like "that works?". The response I got was "of course". In retrospect, I admit that's the right answer: once you get TeX well enough, it's obvious.
