This is a collection of math/logic riddles. The first 80 problems are translated directly from the book "80 brain teasers" published in the early 1990s by ??? in Vietnam and was recently digitalized by Han Ngoc Duc [1].
All problems are family-friendly and should not require a computer to solve. Each problem here should have a logical answer that is not a joke/blunt answer.
They are categorized as follows:
- Trivial: The answer is trivial, has a catch, or widely known by now, should not require coherent/critical thinking.
- Medium: To come up with an answer, you probably need a pen and a paper but there is no catch.
- Hard: A pen and a paper won't save you.
If you want to see the answers or want to discuss your answer, open an issue ticket with the title being the riddle number - For example "Problem 4: Where am I?"
Notes:
1: I do not know whether there exists an equivalent book in English, it does seems like the book has a 100% Vietnamese origin. All translations are mine (Huan), with some delibrate changes in names and such so that it's easier to understand for English speakers. I tried to translate the idea, but not word by word, as some was awfully dated. There are also some outdated illustrations to the problems as well, but I tend to leave them out if they aren't essential to understanding the problem.