When I went on my first promotion course in the Royal Navy our maths instructor handed out log tables and I told him the only log tables I had ever seen were the ones we had picnics on....
For some reason he didn't believe me.... until he realised I was telling the truth and I had to be shown how to use logs..... not that hard in the end....
Never had a slide rule, but my first calculator, bought in Gibraltar in 1975, only did the absolute basic add, subtract, multiply and divide..... and had a seven segment display....
How things have changed!