@MililaniVF (1/3) When I was 16, my mother was building a house in the middle of nowhere. To set cinderblocks for the foundation, we measured the sides and then the diagonals to verify the foundation was square. The diagonal needed to match the Pythagorean theorem, a^2 + b^2 = c^2. One day at the house site 10 miles from civilization, neither of us had a calculator. Despite being shown how by my mother more than once, I still cannot remember how to calculate square roots by hand.