"That's how it's done"

• Math prof's "There you have it"
• Proved, in math
• Concluding letters for a proof reader
• Quantum electrodynamics, abbr
• Letters in math proofs
• Mathematical proof letters
• Relative of "VoilГ !"
• Letters following a proof

Wiktionary Word definitions in Wiktionary
alt. quod erat demonstrandum (Latin ''what had to be proved'' or ''what was to be demonstrated''). interj. quod erat demonstrandum (Latin ''what had to be proved'' or ''what was to be demonstrated''). n. quantum electrodynamics.

The Collaborative International Dictionary Word definitions in The Collaborative International Dictionary
QED \QED.\ (k[=u]"[=e]*d[=e]"), n. Quantum electrodynamics. [abbrev.]