Seven people are blindfolded and given unique colored hats at a roundtable. How should they cooperate for at least one to guess her own color?
An employer hires you to work for 7 days and has a gold bar with 7 segments to pay you with. How do you get them to not break it to pieces?
You are given eight balls that look exactly the same, and a balance to weigh them against each other. Find the odd ball by weighing only twice?