Puzzles
Alcuin's Ox-Drivers Riddle
Two men are driving their oxen down a road. The first says to the second, 'Give me two of your oxen, and I'll have as many as you.' The second replies, 'Now give me back my two oxen, and I'll have twice as many as you.' How many oxen does each man actually have?
Reveal the answer
The first man has 4 oxen, the second has 8 (12 total). Transfer 2 from the second to the first and both have 6 — 'as many as you.' Undo that transfer and you're back to 4 and 8, where 8 is already double 4. One of the oldest trick word-problems on record, from Alcuin of York's Propositiones ad Acuendos Juvenes, compiled around 800 CE.