"The Indian use of subscript dots to indicate the tens, hundreds, thousands, etc., is established by a passage in the Kitāb al-Fihrist (987 A.D.)... The numeral forms given are those which have usually been called Indian, in opposition to ģobār. In this document the dots are placed below the characters, instead of being superposed... The significance was the same."
January 1, 1970
https://en.wikiquote.org/wiki/The_Hindu-Arabic_Numerals