Arithmetic in particular is from India. Indians have a long cultural history of using arithmetic. Even today, my mom who is categorically not a technical person

Arithmetic in particular is from India. Indians have a long cultural history of using arithmetic. Even today, my mom who is categorically not a technical person, will randomly use a computational technique I'd never seen before to do her sewing, cooking or measuring. My grandmother, barely educated, did the same thing. They were extremely good at daily calculations. To the point where whatever I picked up off of them helped me win several 'fast math' competitions as a kid in LA. I'm not particularly good at arithmetic. My guess is that even a not really educated / barely literate Indian kid will be able to do arithmetic, simply due to cultural knowledge. The schoolchildren do well because they've been exposed to logic as well as arithmetic, and also given a systematic overview of the whole thing, whereas the market kid is just applying whatever was passed down culturally. However, I don't think we can necessarily transfer this study outside of India to assume that kids from other areas who are forced to work in markets will be good at arithmetic either. In my opinion, this is a unique cultural condition in India which reflects arithmetic's development there. Indian numerals and arithmetical algorithms were first introduced to Europe in the 13th century. The first records of their use in India go back to the first century AD. Thus, it's had a lot more time to 'soak in' to the common culture. I think it would be a good exercise in 'ethnomathematics' (is that a thing) to document all the algorithms used by the various laborers / uneducated productive workers in India. There'd probably be a few gems there. My two cents; maybe a controversial take.