[QUOTE=GoneTheSun]
I’m surprised it took so long for slide rules to get mentioned.
[/QUOTE]
Circular slide-rules (or computers as they are officially called) are still used by pilots. I am sure I have read somewhere that you need to know how to use one as part of your pilots exam, at least in the UK.
You need to show some proficiency with the E-6B in the US too. But they’re available in cardboard, since they don’t actually get used after that anyway, by anyone who hasn’t been flying for 50 years already and is set in his ways. Nobody even uses flight plans after their written exams, either, not in the GPS era and not in regions like the Northeast with blanket radar coverage. Maybe out in the desert areas they do.
The circular slide rule bezel, as well as the multiple separate dials for sweep second hands and UTC time, is what identifies its proud wearer as an “aviator”. Not the sight of him actually *using * it. 
It seems some species of ants haven’t forgotten Buffon’s needle.
[QUOTE=ElvisL1ves]
Doesn’t anybody use an abacus anymore?
Well, maybe not, used ta be an expert at it wouldn’t need an actual abacus anymore, like a chess expert doesn’t need a chess set.
[/QUOTE]
When I was in Malaysia about ten years ago, the elderly Chinese street vendors still used abacuses. The younger ones had cheapie calculators.