Q. E. D.

Q.E.D. = Quite Easily Done?

At least this is what I have been taught or told.

In actual fact, as it turns out, Q.E.D. is the acronyms of a Latin phrase:

Quod Erat Demonstrandum meaning "this is what I set out to prove"

Example of Q.E.D. being used:

".....thus, the square of the hypotenuse is equal to the sum of the squares of the two legs. Q.E.D."