If you can answer this simple maths puzzle you can consider yourself a maths wizard:
Bill takes the underground train to work and uses an escalator at the
railway station. If Bill runs up 6 steps of the escalator, then it
takes him 82.5 seconds to reach the top of the escalator. If he runs
up 14 steps of the escalator, then it takes him only 62.5 seconds to
reach the top.
How many seconds would it take Bill to reach the top if he did not run up any steps of the escalator at all?