What is the full form of Q.E.D in maths?

Quod​ Erat Demonstrandum.

Quod Erat Demonstradum

Quad Erat demonstradum

"Quod Erat Demonstrandum"

Quod Erat Demonstrandum
Q.E.D. QED is an abbreviation of the Latin words "Quod Erat Demonstrandum" which loosely translated means "that which was to be demonstrated". It is usually placed at the end of a mathematical proof to indicate that the proof is complete.

The full form of 'QED' is 'Quod Erat Demonstrandum'.
 Hope this helps :)

Quod Erat Demonstrandum