Just as I had mastered the slide rule (circa 1972), electronic calculators hit the market.
But, most college professors still forbade their use.
Today, most of the HS students I see can't divide 4 by 2 without a damn calculator.
I bought my first calculator in 1974. It ran on four AA batteries and cost $300. It could do square roots and I needed that for some drug dosing formulas.