The Brahmi numerals are an indigenous Indian numeral system attested from the 3^rd century BCE (somewhat later in the case of most of the tens). They are the direct graphic ancestors of the modern Indic and Hindu-Arabic numerals. However, they were conceptually distinct from these later systems, as they were not used as a positional system with a zero. Rather, there were separate numerals for each of the tens (10, 20, 30, etc.). There were also symbols for 100 and 1000 which were combined in ligatures with the units to signify 200, 300, 2000, 3000, etc.

Origins

The source of the first three numerals seems clear: they are collections of 1, 2, and 3 strokes, like the modern Chinese numerals. However, the other unit numerals appear to be arbitrary symbols in even the oldest

The sometimes rather striking graphic similarity they have with the hieratic and demotic Egyptian numerals is not good evidence of a historical connection, as many cultures have independently recorded numbers as collections of strokes — witness the Roman numerals, for example. With a similar writing instrument, the cursive forms of such groups of strokes could easily be broadly similar as well.

Another possibility is that the numerals were acrophonic, like the Attic numerals, and based on the Kharosthi alphabet. For instance, chatur 4 has a ¥ shape much like the Kharosthi letter ch; panca 5 looks remarkably like Kharosthi p; and so on through shat 6, sapta 7, and nava 9 (Kharosthi sh, s, n).

However, both suggestions are purely speculative at this point, with no evidence to decide between them.