I'm sure I've read a much older short story, possibly by Frank Herbert, where in the future computers do all the calculations so humans have forgotten how to do basic arithmetic. It is rediscovered, only now it's much cheaper to put a human in a missile to perform guidance calculations than using an expensive computer! The HN hive mind will probably remember this better...
EDIT: It was "A Feeling of Power" by Asimov - https://archive.org/details/1958-02_IF/page/n5/mode/2up?view...