Two-two

Three-three

Four-four

Fifth generation

VI - 6

X - 10

L - 50

C - 100

D - 500

M - 1000

There are seven Roman numerals, namely I (1), V (5), X (10), L (50), C (100), D (500) and M (1000). They can be expressed according to the following rules.

Repeat several times: A Roman number repeated several times means several times this number. For example, "three" means "3"; "XXX" means "30"

Add right and subtract left: write a smaller Roman numeral to the right of the larger Roman numeral, indicating that the larger number is added with the smaller number, such as "VI" for "6" and "DC" for "600". On the left is a symbol representing a large number, which means subtracting a large number from a decimal, such as "IV" for "4" and "XL". "VD" stands for "495" Although a smaller Roman number is written to the left of a larger number, which means that the larger number reduces the number, the subtraction on the left cannot cross levels. For example, 99 can't be represented by IC, but only by XCIX.

Multiply a Roman numeral by adding a horizontal line above it or writing m at the bottom right, which means that this number is multiplied by 1000, which is 1000 times the original number. Similarly, if it has two horizontal lines on it, it is 100000 times the original number.

Company limit: the same company can only appear three times. For example, 40 cannot be expressed as XXXX, but as XL.