Enigma 52: Think of a number
30 January 2013
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From New Scientist #1195, 21st February 1980 [link]
The little Buggins were given a games-playing robot for Christmas and are fascinated still. Among its games is a fearsome version of the old Victorian pastime now marketed as Mastermind. The robot thinks of a number and you try and deduce what it is by proposing a series of numbers with the right number of digits. After each guess the robot shows one flashing light (F) for each correct digit correctly placed and one steady light (S) for each correct digit wrongly placed. Thus, if it chose 98766 and you guessed 66765, it would show FFS.
The machine can handle any number of digits up to nine but the Buggins kids are only human and are having trouble enough with five-digit numbers. Here, for instance, is a series of five guesses and the robot’s comments:
1 2 3 4 5 FFS
3 1 6 2 0 SSS
7 3 8 9 0 FS
8 9 5 1 4 F
6 0 1 7 1 FSS
What do you reckon the robot’s number is?
Enigma 147 and Enigma 262 are also called “Think of a number”.