By the title, you might think that “ethnomathematics” might be a means to count or calculate the number of people in this or that ethnic group. Nope.
Originally it seems to have been the study of how different cultural groups did math or at least understood the concepts of numbers and counting. But recently it has taken a far more sinister turn, and has become the nonsensical notion that mathematics is somehow subject to ethnicity, that this ethnic group has a different set of math than others. That multiplication and division and simple addition are different from one group to another. And that some primitive form of math that struggles to count to ten is somehow relevant in the modern world and that limited educational time and resources should be splurged on teaching kids ineffective, outdated and really rather useless ways of doing math purely to make some people feel good about their mythical past. It is in effect, if not necessarily in intent (though I would not bet against intent), a means by which a population can be rendered incompetent to even *understand* their own technological underpinnings.