The Hindu-Arabic Numerals c8.21

c8.21

The small circle was possibly suggested by the spurred circle which was used for ten.³ It has also been thought that the omicron used by Ptolemy in his *Almagest*, to mark accidental blanks in the sexagesimal system which he employed, may have influenced the Indian writers.⁴ This symbol was used quite generally in Europe and Asia, and the Arabic astronomer Al-Battānī⁵ (died 929 a.d.) used a similar symbol in connection with the alphabetic system of numerals. The occasional use by Al-Battānī of the Arabic negative, *lā*, to indicate the absence of minutes (or seconds), is noted by Nallino.¹ Noteworthy is also the use of the ⚬ for unity in the Śāradā characters of the Kashmirian Atharva-Veda, the writing being at least 400 years old. Bhāskara (*c.* 1150) used a small circle above a number to indicate subtraction, and in the Tartar writing a redundant word is removed by drawing an oval around it. It would be interesting to know whether our score mark ④, read “four in the hole,” could trace its pedigree to the same sources. O’Creat² (*c.* 1130), in a letter to his teacher, Adelhard of Bath, uses τ for zero, being an abbreviation for the word *teca* which we shall see was one of the names used for zero, although it could quite as well be from τζιφρα. More rarely O’Creat uses o, applying the name *cyfra* to both forms. Frater Sigsboto³ (*c.* 1150) uses the same symbol. Other peculiar forms are noted by Heiberg⁴ as being in use among the Byzantine Greeks in the fifteenth century. It is evident from the text that some of these writers did not understand the import of the new system.⁵