A rule of mathematical style: it is acceptable to write "Therefore, foo is at most bar.", but it is not acceptable to write "Therefore, F ≤ B." (This is due to J. Michael Steele, who has a lot of good rants.)
Steele's logic is that mathematical symbols cannot function as the verb in a natural-language sentence, which makes sense; although mathematical expressions have their own internal logic, an entire expression seems to function as a single noun when embedded in an English-language expression. Thus we write something like "Therefore, we have F ≤ B." or "Therefore, the inequality F ≤ B holds." ifwe want to write things out in symbolic form.
One thing that bothers me about a lot of mathematicians (myself included) is the propensity for their spoken mathematics to be a mere symbol-by-symbol reading of the written mathematics; thus one hears things like, say, "pi one of X" instead of "the fundamental group of X". This isn't too much of a problem in that case, but then one gets to things like "H two of X" -- is that H2(X) (homology) or H2(X) (cohomology)? (People don't seem to go to the trouble of distinguishing superscripts from subscripts when they're talking, which is probably a good thing, lest speech be filled with "uppers" and "lowers".)
Sure, you can usually tell from context, if you're sufficiently experienced in a certain area. But people have a tendency to think that mathematics is the formulas, at least to the point where they speak the notations instead of the notions. (This is one of those fortunate puns that translates well from the original Latin: "non notationes, sed notiones".) Spoken mathematics is not written mathematics. Mathematics is not its notation.
This is probably a corollary of the often-stated fact that a page of mathematical text contains about as many ideas as, say, ten pages of "ordinary" text; thus on a per-page basis, mathematical reading should be ten times slower than literary reading. Unfortunately, a minute of mathematical speech contains many more ideas than a minute of "ordinary" text, but one cannot slow the speaker down.
Incidentally, I used to pronounce ≤ and ≥ as "less than or equal to" and "greater than or equal to"; now I pronounce them "at most" or "at least", because these are shorter. I also pronounce g o f as "g after f", which seems both shorter and less ambiguous than "g composed with f" -- in "g composed with f" the order of composition is conventional. "f before g" or "f, then g" is too confusing, because you read the g before you read the f.