From Electronic Life:
In 1967, all students at the Harvard Medical School were required to take a biostatistics course. At this time there was a newly emergent class of specialist, called biostatistician, who was consulted by working biologists with the same frequency that Mafia hit men consult their lawyers, and for the same reason - to ask, "Can I get away with this?" Is my work unobjectionable?"

Thus in 1967, to teach biostatistics to every medical student had its revolutionary aspect; the idea was to make all young doctors self-sufficient to carry out their own statistical analyses, and to evaluation those of others. It was imagined we would read every journal article critically, and then sit down with pencil and paper to scratch out the calculations and determine if the authors had done their sums correctly or not.

But his focus on self-reliance (and a rather prissy instructor) led to a final examination where we were expected to calculate standard deviations by hand. And the calculation of standard deviations requires the calculation of square roots by hand.

I'd done a lot of statistical work before medical school, and although I setup the formulas on paper for my final, I flatly refused to do these calculations by hand. Desk-top calculators were available for such drudgery; every lab had them. I pointed this out.

And I went further. I predicted that within ten years there would be calculators the size of a pack of cigarettes, and costing only a hundred dollars. Thus, I argued, there was no need to bother doing square roots by hand, since it as a virtually obsolete skill.

For this bit of prediction, I got a sarcastic note in red pencil, and a D grade. My instructor took pains to remind me that desk-top calculators in 1967 were larger than a typewriter, weighed more that thirty pounds and cost several hundred dollars. My instructor disagreed that they would ever become as small and cheap as I claimed in my lifetime, let alone in ten years. He made some further nasty remarks about my propensity for science fiction, and underlined the D grade twice, emphatically.

Texas Instruments sold the first pocket calculators in 1971.