School children nowadays have it easy with the Objective system: multiple choice answers are given - they only need to choose which they think is the right answer. During my time we had to 'prove' everything.
In primary school shortly after the war I enjoyed and always looked forward to the three 'R' classes: Reading, (W)'Riting, and (A)'Rithmetic. Then the Arithmetic got more complex as we were introduced to Geometry and Algebra.
We had an excellent if a bit of a show-off Arithmetic teacher. Always one who would gleefully throw us one arithmetic challenge after another, he always thought he's better than any of us at Arithmetic (as a teacher wasn't he supposed to be?).
When we had problems with geometry or algebra questions, he would gladly demonstrate the workings and proudly showed us how he arrived at the answers.
Always brightly attired, and with equally colorful language, he would tell us how easy it was to solve them. He would pace enthusiastically up and down the classroom, then approached and wrote one 'working' line after another on the chalk board.
At the end of his animated 'performance' he would loudly declare: "Quod Erat Demonstrandum", and wrote down in big capitals: Q.E.D at the bottom of his workings, looking quite pleased with himself.
Q.E.D (or in Greek ΟΕΔ) is Latin for "What was to be demonstrated or proven" *
Over time Q.E.D meta morphed into its own English version as Quite Easily Done. Which is more than I can say for this A-Z Challenge.
*In French it is C.Q.F.D - ce qu'il fallait demontrer (sorry I do not possess any accent on my keyboard, do they actually have keyboards with accents?)
Italian - C.V.D - come volevasi demostrare
Irish - R.B.T - an rud a bhi le taispeaint