Roman numerals use symbols to represent numbers, with I=1, V=5, X=10, L=50, C=100, D=500, and M=1000. Numbers are written by combining symbols, with smaller values subtracted from larger ones to the left. For example, IV=4 and IX=9. Only one digit can be subtracted at a time. Roman numerals cannot have a number subtracted that is more than 10 times larger. Practice problems are provided to convert between Hindu-Arabic and Roman numerals.