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The Ciphers of the Monks: a Forgotten Number-notation of the Middle Ages) is a book by David A. King.
Contents
Content
The book describes, in detail, a numeral system that was commonly used by European monks in the Middle Ages. That number system allowed one to write numbers from 1 to 9999 with minimum of strokes. This numeral system later fell out of use.
The cipher
The system uses a vertical straight line as its main symbol. This symbol is essentially an axis that divides the two-dimensional plane into four quadrants. Each of these four quadrants signifies one of the four digits. The number can then be determined by visual inspection.
The numeral system was invented in the 1300s by French Cistercian monks. It was later replaced by the Hindu–Arabic numeral system. In any case, this numeral system later inspired several shorthands and secret ciphers.
In Britain, the first person to use this cipher was John of Basingstoke.
Reviews
The book has generally received positive reviews.