Mathematician David Reimer on how Ancient Egyptians did their maths, and how it was different from modern mathematics.
In an article for The College of New Jersey (where Reimer is a math professor) he says:
the Egyptian way of thinking about math is deeply satisfying. “Today, we’re taught to do math in a step-by-step way—you do this step, then this one, then this one. If you follow exactly what you’re told, you get the right answer,” Reimer says. “But in Egyptian math, there are any of maybe five to eight tools that you can apply. It’s not a mindless algorithm; it’s more like a Sudoku puzzle.”
And he wrote a book about it: