Here's an amusing piece of basic math that is relevant to physics
as well as finance and (!) pandemics.
There are situations where thinking in terms of percentages is
problematic, and centinepers work better, especially when the range of
variation is bigger than a few percent. For example, suppose we are
measuring something that might change by an amount proportional to the
previous amount. This could be radioactive decay, compound interest,
stock market fluctuations, the spoilage of milk, or the spread of a
pandemic.
This applies to how we formulate our thoughts, as well as communicate
our thoughts. In particular, it applies to the units on log and semi-log
plots.