another interesting math riddle

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from the front cover insert of the Penguin Dictionary of Curious & Interesting Geometry…
David Wells was born in 1940. He had the rare distinction
of being a Cambridge scholar in mathematics and
failing his degree. He subsequently trained as a teacher
and, after working on computers and teaching machines,
taught mathematics and science in a primary school and
mathematics in secondary schools. He continues to be
involved with education through writing and working
with teachers.
While at university he became British under-21 chess
champion, and in the middle seventies was a game inventor,
devising 'Guerilla' and 'Checkpoint Danger', a
puzzle composer, and the puzzle editor of Games and
Puzzles magazine. From 1981 to 1983 he published The
Problem Solver, a magazine of mathematical problems
for secondary pupils. He has published several books of
problems and popular mathematics, including Can You
Solve These? and Hidden Connections, Double
Meanings, and also publishes the journal Studies of
Meaning, Language and Change. He has written The
Penguin Dictionary of Curious and Interesting Numbers
and recently published a book comparing the psychology
of the Russians with that of the West.
sic: bold my emphasis
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BEST!
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