During a math exam, Willy asks Ms. Matilda, the teacher, how much time is left. Ms. Matilda is known for being obtuse and answers that the amount of time left is 1/5 of the time already completed and that is also how much time is left, in a manner of speaking.
15 minutes. The total exam time is 90 minutes. If 15 minutes are left, 75 minutes have already passed, and one fifth of 75 is 15. However, if you follow Ms. Matilda’s hint and pay attention to only the numbers in 1/5, you get the answer of 15 minutes as well.
A man is trapped in a room with only two possible exits. Through the first door is a room with an enormous magnifying glass causing the blazing hot sun to instantly burn anything that enters. Through the second door there is a fire-breathing dragon. How does the man escape?
The most popular answer for this teaser is ‘today’. Of course this only works if you’re reading it on that particular date or if the date is not specified. Another option is to respond literally with ‘a date’. Lastly, certain dates could be squeezed into letters using Roman numerals if you abbreviate the year to 2 numerals. For example, January 20th, 2011 would be I XX XI.
This problem can be solved by preschool children in five to ten minutes, by programmers in an hour and by people with higher education…well, check it yourself.