One way to detect mathematicians is that we say "[...], in particular, [...]". I guess it's our version of the economist thing!

Mathematicians and computer scientists will also say

  "for all" / "there exists" instead of "every" / "there's at least one"
  "let" as an imperative for establishing facts
  "fix" for choosing a value
  "given" instead of "if"
  "modulo" instead of "except for"
  "if, and only if," when the occasion warrants it
  "implies" instead of "means"
  "trivial" without intending to be mean
  "yes" when asked an "or" question
  "transitively"
  "by symmetry"
  "it follows"
  "canonical"

You can say a lot with few words when you have rich definitions.

I know when they say "such that ..."