I think there's a lot to be said for the abacus, jettons, slide rules and other pre-electronic mathematical aids, as well as simple pen-and-paper calculation.

I think there's a lot to be said for the abacus, jettons, slide rules and other pre-electronic mathematical aids, as well as simple pen-and-paper calculation. Those mathematical aids tend to help one see how numbers and functions move and change over a space so that one develops an intuition for a range of problems, rather than just get an answer to a specific question.