Cistercian numerals - Wikipedia
The medieval Cistercian numerals, or “ciphers” in nineteenth-century parlance, were developed by the Cistercian monastic order in the early thirteenth century at about the time that Arabic numerals were introduced to northwestern Europe. They are more compact than Arabic or Roman numerals, with a single glyph able to indicate any integer from 1 to 9,999.
It’s such a cool system where single digits are defined by to the top right, tens in top left, hundreds in bottom right and thousands in bottom left and each digit’s symbol is the same in all multitudes. With a bit of practice, you can really quickly decipher the numbers into decimal.