Q.E.D.

Q.E.D.

A Mathmeticians way of saying "I win".

Thanks to Urban Dictionary.

Q.E.D.

An abbreviation of the Latin phrase "quod erat demonstrandum" (literally, "that which was to be demonstrated").

The phrase is written in its abbreviated form at the end of a mathematical proof or philosophical argument, to signify that the last statement deduced was the one to be demonstrated, so the proof is complete.

Thanks to Wikipedia.