$\times$ as symbol for multiplication, how common is this?

Question

I never encountered the $\times$ symbol denoting multiplication (of real numbers or real-valued functions) since middle school until I found it recently in the measure theory notes by D H Fremlin. Since it seems to me that this author writes in a quite consistent and well-considered style, I just wondered if there is any philosophy behind the use of this symbol and, more important, if other working mathematicians would immedeatly get what is meant by it or if they would, like me, be a little bit puzzled at first.

Answer 1

I find that $\times$ is not used often. The problem is that it looks like $x$, especially in print. I see it used most often when only working with numbers. Something like $4\times9+4$, or when $\times$ means something specific like the cross product. It may also be used for Cartesian product.