The Cistercian Numeral System of the 13th Century Writes Numbers up to 9999 with a Single Sign
Never mind whether you remember your Roman numerals: today we learn medieval ciphers. Or, more precisely, the Cistercian system of numeration, devised by learned monks in the thirteenth century. The Cistercian system of counting allows any number up to 9999 to be written with a single sign. Take a look at the cipher, it is all rather simple: one need only memorise nine combinations attached to a single vertical line, while the reflection of the same combination determines the place value, and when several registers are combined in one glyph, the result is the numbers that are not round.