The Roman numeral for 1 is I, 2 is II and 3 is III. The Roman numeral for 4 is IV, 5 is V, 6 is VI, 7 is VII and 8 is VIII. The Roman numeral for 9 is IX, and the Roman numeral for 10 is X.
The numbers continue in this pattern. Up to three digits may come after the number and up to one digit may come before, so 11 is XI [10(X) + 1(I)], 12 is XII, 13 is XIII and 14 is XIV [10(X) + 4(IV)]. The numeral for 50 is L, 100 is C, 500 is D and 1000 is M.
After 1000, a line drawn above the numeral indicates that the number is 1,000 times that amount. A V with a line over it would indicate 5,000, and an X with a line over it would indicate 10,000. A C with a line over it would indicate 100,000, and an M with a line over it would indicate the number 1,000,000. The Romans did not have a symbol for zero.
Roman numerals are generally used today to indicate copyright dates and the order of rulers or ships that share the same name.