I ran into an interesting subreddit recently - r/confidentlyIncorrect
Simple math blunders are quite popular there, after reading dozens of them a pattern emerged.
Usually it's in the form of if you have 600 million dollars and there are 300 million americans, you can give every american 2 million dollars - notice what's going on here - treat the numbers and the descriptors as separate things - so 600/300 = 2, and append "million".
The other popular post on there is "solve <simple problem statement>, DONT USE CALCULATOR", that usually involves order of operations and never has any parentheses. [
Example]
Some people never acquire the correct mental models to deal with even simple math. As a programmer - they tokenize the sentences all wrong. For most people "600 million" is one token that gets converted into the mental representation of a large number. For others "600" and "million" is separate.
I have like a tier list of common mathematical confusion:
1. 600-million class, like above.
2. Order of operations class.
3. Percentages - they are quite tricky.
4. Probability - human brains not built to handle this well (or probably just not educated)
For myself, I find that 1 and 2 are automatic, 3 sometimes automatic, sometimes I have to stop and think whether a situation falls into the weird edge case, 4 - stop and carefully think through the situation 90% of the time.
