Cistercian Monk Numerals

The numeral system of Cistercian monks uses a quadrant (in 4 parts) to represent numbers from 0 to 9999.

Any number necessarily consists of a central vertical bar, if nothing else is written, then it takes the value 0, otherwise, the quadrant at the top right corresponds to the units, the quadrant at the top left for the tens, the quadrant at the bottom right for the hundreds and the last quadrant at the bottom left for the thousands.

There are then 9 symbols to represent the numbers (here the units):

1		2		3
4		5		6
7		8		9

Rotate/mirror these symbols to write them in the right quadrant.

Example: 5555 is written

Decompose the symbol in 4 quadrants and find the corresponding figure for the thousand (bottom left), hundreds (bottom right), tens (top left), units (top right).

Example: is read 3579

Numbers are composed of line-based symbols in 4 corners.

All references to the Cistercian order and the (french) monks are clues.

This numeral system was popularized by David A. King's book entitled The Ciphers of the Monks: a Forgotten Number-notation of the Middle Ages

In the 14th century