That is such a useful feature. I had a Casio calculator with a button called "Eng" which did something similar. It was incredibly useful for converting an answer to k. M, G etc.

I actually think the mid 1980s was when calculators peaked. You could get scientific calculators like the above that were packed with every function you actually needed (note the calculator above had stats, hex and even complex) but none of the bullshit that later became popular like direct arithmetic entry and calculators that give you answers as fractions. The thing is that computers were not ubiquitous yet so real life professionals like engineers and scientists actually used calculators every day and they had to be functional. Nowadays calculators only seem to be used by students.