In history mathematics was not for everyone[0], not in the same sense as isn't today. IMHO, having chance to learn mathematics is a privilege. Most people not e

In history mathematics was not for everyone[0], not in the same sense as isn't today. IMHO, having chance to learn mathematics is a privilege. Most people not even have chances to train "mental arithmetic", "mental survival" is more likely a thing. Sorry for not answering your question. [0]: https://blogs.scientificamerican.com/guest-blog/mathematicians-are-overselling-the-idea-that-math-is-everywhere/ https://blogs.scientificamerican.com/guest-blog/mathematicia...