• Math

    Brainteaser: Forehead Numbers

    There are 3 people placed in a room.  They all have perfect logic.  The 3 people are told by a host that a number has been written on each of their foreheads.  Each of the 3 numbers are unique, they are all positive, and they relate to each other such that A + B = C (i.e. one is the sum of the other two).  In the room, each person can only see the other two people’s numbers, as they cannot see their own foreheads.   Suppose you are one of the 3 and you see one person with “20” on their forehead and the other person with “30.”  The…