> The reason why people can't do that calculation in their heads is because of our reliance on computers and calculators. No, we were never well equipped to do

> The reason why people can't do that calculation in their heads is because of our reliance on computers and calculators. No, we were never well equipped to do such computations, we didn't suddenly get worse at it with the invention of calculators. Consciously aware mental calculation is a very recent thing on an evolutionary time scale. I think even 10-20k years ago no one did any mental calculations beyond the most trivial arithmetic operations. OTOH we have a pretty cool native physics engine in our brains and can solve pretty challenging problems such as predicting trajectories and modeling fluid flow. These skills were much more useful in our evolutionary past than arithmetic or algebra.