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?
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Answer to Enigma 819
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