Something for the weekend, Sir?
Here's a screenshot of a document I put together many years ago - I usually have a printed version somewhere I can see or reach quickly (in a notebook or on a noticeboard). The ones I commonly use like °, ö, ü, ä, é I know from memory now, others I can usually get to with a few guesses. I hate seeing lazy/ignorant use of things like º (superscript 0) instead of ° (degree) and even x (lower case x) instead of × (multiply). The grey-backed characters will work almost universally across different programs but the amber ones I usually have to go to MS Word to type them and then copy/paste to my required location (eg ≈).
For some I have created automatic replace options in Windows - so for example if I type (C) it will auto-replace to © or CO2 will become CO₂.
View attachment 587574