How Roman numerals work
Roman numerals use seven symbols: I=1, V=5, X=10, L=50, C=100, D=500, M=1000. When a smaller value precedes a larger one, it is subtracted: IV=4, IX=9, XL=40, XC=90, CD=400, CM=900. The system handles numbers from 1 to 3999 without a symbol for zero.