Another possibility is that the numerals were acrophonic, like the Attic numerals, and based on the Kharoṣṭhī alphabet. For instance, 4 "chatur" early on took a shape much like the Kharosthi letter 𐨖 "ch", while 5 "pancha" looks remarkably like Kharosthi 𐨤 "p"; and so on through 6 "ssat" and 𐨮, then 7 "sapta" and 𐨯, and finally 9 nava and 𐨣. However, there are problems of timing and lack of records.