一切經音義 17.13

17.13

千姟（改孩反算經云十萬曰億十億曰兆十兆曰京十京曰姟數法名也古今正字云大也數也從女亥聲經從土誤用也）。

千姟 (fanqie: 改 + 孩; the Suanjing says: "A hundred thousand is called an yì (億); ten yì are called a zhào (兆); ten zhào are called a jīng (京); ten jīng are called a gāi (姟)." It is a name for a numerical order. The Gujin zhengzi says: "It means great; a number. It is classified under woman (女) and takes 亥 as phonetic." In the sūtra it is written with earth (土 as phonetic/radical), which is an erroneous usage).