section_path: Description/Large numbers/Apostrophus
section_name: Apostrophus
paragraph_text: Apostrophus
  
  Using the apostrophus method, 500 is written as IↃ, while 1,000 is written as CIↃ. This system of encasing numbers to denote thousands (imagine the C s and Ↄ s as parentheses) had its origins in Etruscan numeral usage.
  
  Each additional set of C and Ↄ surrounding CIↃ raises the value by a factor of ten: CCIↃↃ represents 10,000 and CCCIↃↃↃ represents 100,000. Similarly, each additional Ↄ to the right of IↃ raises the value by a factor of ten: IↃↃ represents 5,000 and IↃↃↃ represents 50,000. Numerals larger than CCCIↃↃↃ do not occur.
  
  Sometimes CIↃ (1000) is reduced to ↀ, IↃↃ (5,000) to ↁ; CCIↃↃ (10,000) to ↂ; IↃↃↃ (50,000) to ↇ; and CCCIↃↃↃ (100,000) to ↈ. It is likely IↃ (500) reduced to D and CIↃ (1000) influenced the later M.
  
  John Wallis is often credited with introducing the symbol for infinity ⟨ ∞ ⟩, and one conjecture is that he based it on ↀ, since 1,000 was hyperbolically used to represent very large numbers.