The long hundred, или 120=100, а 12=10

[nordickk]

Ух ты: The long hundred, great hundred, or twelfty[1] is the "hundred"  of six score (120) used in Germanic languages prior to the 15th century.  The number was simply described as hundred and translated into Latin in  Germanic-speaking countries as centum (Roman numeral c.)
https://en.wikipedia.org/wiki/Long_hundred

Получается что 120 могло перейти в 100, а 12 = "C" в 10.