section_path: Other uses/Use as numerals
section_name: Use as numerals
paragraph_text: Use as numerals
  
  Greek letters were also used to write numbers. In the classical Ionian system, the first nine letters of the alphabet stood for the numbers from 1 to 9, the next nine letters stood for the multiples of 10, from 10 to 90, and the next nine letters stood for the multiples of 100, from 100 to 900. For this purpose, in addition to the 24 letters which by that time made up the standard alphabet, three otherwise obsolete letters were retained or revived: digamma ⟨ Ϝ ⟩ for 6, koppa ⟨ Ϙ ⟩ for 90, and a rare Ionian letter for, today called sampi ⟨ Ͳ ⟩, for 900. This system has remained in use in Greek up to the present day, although today it is only employed for limited purposes such as enumerating chapters in a book, similar to the way Roman numerals are used in English. The three extra symbols are today written as ⟨ ϛ ⟩, ⟨ ϟ ⟩ and ⟨ ϡ ⟩. To mark a letter as a numeral sign, a small stroke called keraia is added to the right of it.