The most amazing numbering system that you’ve never heard of.
Cistercian Numerals were created in the thirteenth century (CE) by the Cistercian monastic order. They look a lot like Norse Runes but they are actually a very cleaver numbering system that allows you to store any value between 1 and 9,999 in a single digit.
In essence it uses a repeating pattern based around a central line, the pattern begins to the top and to the right of the line for representing the numbers 1-9 i.e. your units. The tens are then represented as a reflection of that pattern to the left of the central line. Hundreds are again a reflection of the pattern in the bottom right and thousands a reflection in the bottom left. Below are some examples of what this looks like for some larger numbers: