Calculators - 50-30 years old

In searching for a piece of electronics I came across my old slide ruler (‘Unique’ Universal II Slide Ruler) from my days at secondary school (1960’s) on which you could calculate all your basic maths (add, subtract, divide), trigonometry (Sine, Cosine, Tangent etc.) and log calculations.

The Casio solar powered fx-411 calculator (bought in 1984), which I still use today, was a very useful tool in my electronic engineering and software engineering days.