It's a little tricky to explain the Cistercian number system using words — it's made of stick-like figures, after all — but we'll do our best. The system might seem tricky, but only at first. Ultimately, it makes a heck of a lot of sense, and maybe makes for some fun cryptographic shenanigans on the side.
To write a Cistercian number start with a single vertical line — easy. That line will always be present no matter what number you write. Then, imagine the line bisects four quadrants that proceed in this order: upper right of the line, upper left, lower right, lower left. Upper right contains the "ones" digits: 1 through 9. Upper left contains the "tens" digits: 10, 20, 30, 40, etc. Lower right contains the "hundreds" digits: 100, 200, 300, 400, etc. Lower left contains the "thousands" digits: 1000, 2000, 3000, 4000. We're not too sure what happens when you reach 10,000 or more, but you could always just add two or more glyphs together. The system is flexible, anyway.
In each quadrant you make a little mark, and those marks are consistent by digit across all quadrants. For example: 5, 50, 500, and 5000 are little flags. Nine, 90, 900, and 9000 are boxes. Depending on the number, you make an appropriate mark in each quadrant, and bam: You've got one figure for one number, no matter how complex.
[Featured image by Meteoorkip via Wikimedia Commons | Cropped and scaled | CC BY-SA 4.0]
