The numeral forty is comprised of four units of ten.
Illustrative Text Reference:
Chanhujo-daro: Copper object: C-40 A: Jagat Pati Joshi and Asko Parpola, 1987: Corpus of Indus Seals and Inscriptions: Volume 1: Page 338: Collections in India: Suomalainen Tiedeakatemia.
Comment:
This is my reading of the photograph of artifact C-40. Please note that the inscription is not very clear. It is therefore, possible that sample text C-40 does not include the numeral forty.
Image Credit:
Numeral Forty: Lynn Fawcett, 2018.