Some trading and finance firms screen candidates with a fast arithmetic test: 80 questions in 8 minutes, multiple choice, no calculator, and a point off for each wrong answer. That's 6 seconds a question, and the options are only one slip apart, so estimating isn't enough.
The scoring changes the strategy. A wrong answer costs as much as a right one earns, and with four options a blind guess loses you half a point on average. Skip anything you can't work out with confidence; skipping is free.