Unsolved problems Mathematical research often concerns questions which are so abstract and technically complicated that only a small number of experts in that particular field can fully understand the problems and their significance. Therefore one is easily led to the conclusion that every problem is difficult to understand. This is not so. On this page I have gathered a handful of problems which to my knowledge and to this date are still unsolved although they can be understood by any one who has a working knowledge of, say, the high-school mathematics curriculum.
Nobody knows, but most mathematicians seem to think that it is true.
Two consecutive odd numbers which are both prime are called twin primes, e.g. 5 and 7, or 41 and 43, or 1,000,000,000,061 and 1,000,000,000,063. Start with any positive integer. If it is even, divide it by 2, else multiply it by 3 and add 1. Take a square napkin. Keep in mind that these problems may seem simple, but they have recieved considerable attention during the years, and many prominent mathematicians have tried to solve them.