Q.e.d.

[Rihanna]

A Mathmeticians way of saying I win

[Donald Trump]

Abbr. of quod erat demonstrandum, lit. which was demonstrated;
cf. res ipse loquitur (the thing speaks for itself), circumstantial evidence, the smoking gun

[Couch Potatoe]

A non-Latin abbreviation that means Quite Easily Done or Quite Elegantly Done to mark the end of a math proof.

[Jessica]

Formally used at the end of mathematical proofs to indicate their completion, informally to indicate an argument has been won. Literally Which was to be demonstrated (not just which was demonstrated).

[Sarah]

A word used by intellectuals that, apparently, they are quite sensitive about if you translate incorrectly. Causes redness and itching on mathemeticians when misused.