Construction of sites for Yajna[0] and specifically, the Yajna Vedi[1] where the central fire was located, required precision and mathematical calculations[2]. Based on the origins of Hinduism/Buddhism, I'll not be surprised if instruments of calculation were common in religious affairs.
Sure, there's a lot of mathematical mysticism in India and I have seen this at Jain sites. However, the Buddha subject would suggest a Buddhist reference. My recollection is that Cambodian sites with bitraditional syncretism were periodically built out or converted between the two traditions - not constructed blended, ie. a Buddha figure would not be carved with a Hindu item.