Arabic numerals
The first mentions of the numerals in the West are found in the "Codex Vigilanus" of 976.
Legacy of the Roman Empire
Roman numerals continued as the primary way of writing numbers in Europe until the 14th century, when they were largely replaced in common usage by Hindu-Arabic numerals. The Roman numeral system continues to be widely used, however, in certain formal and minor contexts, such as on clock faces, coins, in the year of construction on cornerstone inscriptions, and in generational suffixes (such as Louis XIV or William Howard Taft IV). According to the Royal Spanish Academy, in the Spanish language centuries must be written in Roman numerals, so "21st century" should be written as "Siglo XXI".