Eli Tyre comments on What are some triggers that prompt you to do a Fermi estimate, or to pull up a spreadsheet and make a simple/​rough quantitative model?

[Eli Tyre]

I probably do basic sanity checks moderately often, just to see if something makes sense in context. But that’s already intuition-level, almost.

If it isn’t too much trouble, can you give four more real examples of when you’ve done this? (They don’t need to be as detailed as your first one. A sentence describing the thing you were checking is fine.)