What’s something most people don’t understand?

I’ve been wondering what to write for this prompt, and I realise that apart from basic addition (arithmetic) people struggle with calculations and formulas.

I was dropped down into the CSE group when I did maths at school. In the end that did me a favour. The exam was like a normal lesson and I got an o level pass.

I just about understood quadratic equations but never liked having to go through the stages of the calculations. I could follow logarithms, but never did calculus. My understanding of sine, co-sine and tangents left something to be desired.

But at least I understood numbers. There is something like dyslexia that some people have, it’s called dyscalculia. As people become aware of it, it might explain why they struggle.