Today's 25

Hello doctor. We know you are busy.

How many questions do you have time for today?

Tap your answer and you see at once whether it was right, with the rule it rests on and where it comes from. Your answer is final the moment you tap it.

You are marked only on what you answer. Stop any time - eight answered is marked out of eight, and the eight still count towards the day.

Twenty-five questions a day, and that is the lot. Take them in one sitting or in three; every answer counts the same. A new 25 opens at midnight.