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Roman numerals are the symbols used in a system of numerical notation based on the ancient Roman system. The symbols are I, V, X, L, C, D, and M, standing respectively for 1, 5, 10, 50, 100, 500, and 1,000.

A symbol placed after another of equal or greater value adds its value.

e.g.

• II = 1 + 1 = 2
• LVII = 50 + 5 + 1 + 1 = 57

A symbol placed before one of greater value subtracts its value.

e.g.

• IV = −1 + 5 = 4
• XC = −10 + 100 = 90
• CD = −100 + 500 = 400

A bar placed over a number multiplies its value by 1,000.

e.g.

• V̅ = 5 x 1000