A thief pays for a £15 bike with a worthless cheque and pockets £10 change
A cyclist bought a bicycle for £15 and paid with a cheque for £25. The seller got a neighbour to cash it, handed the cyclist his £10 change, and the cyclist rode off. The cheque turned out to be worthless, so the seller had to borrow £25 to repay his neighbour. The bicycle itself had cost the seller £11. How much did the seller lose in total?
Reveal the answer
£21 — the £11 the bicycle cost him, plus the £10 cash change he handed over. The cheque and the borrowed £25 are red herrings that cancel out and add nothing to the loss. From Henry Dudeney's Amusements in Mathematics (1917), puzzle No. 38.
— Henry Dudeney, Amusements in Mathematics — Thomas Nelson & Sons, 1917, Puzzle No. 38
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