If the interest rate on a savings account is 0.02%, approximately how much money do you need to keep in this account for 1 year to earn enough interest to cover a single $9.99 below-minimum-balance fee?

This question seems to be a good example of why we need to learn math!

P=present value
i=interest rate = 0.02 per year
time, t=1 year
we need P such that
interest = Pit ≥ 9.99
or
P(.0002*1) ≥ 9.99
=>
P ≥ 9.99/0.0002 = 49950

it takes a minimum balance of $49950 to cover a "below minimum balance fee" of $9.99.