TITLE: Does $x/yz$ mean $x/(yz)$ or $(x/y)z$?
QUESTION [7 upvotes]: When people write $x/yz$, do they usually mean $x/(yz)$ or $(x/y)z$?
For example, from Wikipedia

If $p\geq 1/2$ , then  $$  \Pr\left[ X>mp+x \right] \leq
 \exp(-x^2/2mp(1-p)) . $$

Thanks!

REPLY [3 votes]: I was told once by a senior engineer that the last explicit symbol is what counts, it cancels the action of the previous one. So, for example, xyz/abc means $(x*y*z)/(a*b*c)$ and xyz/ab*c means $(x*y*z)/(a*b)*c$, as expressed by any standard computer language.
I was a little upset by that implicit convention, but soon found out that it worked well and 
was able to understand all old handbooks, where equations were written straight in a single line.
I suppose aesthetics is what counts here. I have the feeling that our need for explicit symbols came with a generation which had computer programming lessons at college, so a relatively new thing starting at what, the 60's, the 70's?