A FEW years ago I was given a novelty digital clock which displays the date and time in a ten-digit display (for example 25.12.89/05.08 and 17.02.90/17.57).
The clock has an unusual feature: it buzzes whenever the ten displayed digits are all different. This took me by surprise the first time it happened shortly after I had plugged it in, but then it only happened again after many months – just over a certain number of months later.
How many months?
A £10 book token will be awarded to the sender of the first correct answer opened on Thursday 6 July. The Editor’s decision is final. Please send entries to Enigma 825, Â鶹´«Ã½, King’s Reach Tower, Stamford Street, London SE99 0BB. The winner of Enigma 819 was D.C. Moulton of Crawley, West Sussex.
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Answer to Enigma 819
The money mountain
86 grants.
