The Collatz Conjecture is a very well known problem, partly because it is very easy to understand. It's also a very difficult problem. Terry Tao (the author) i

The Collatz Conjecture is a very well known problem, partly because it is very easy to understand. It's also a very difficult problem. Terry Tao (the author) is one of the top mathematicians in the world and this appears to be a significant step towards proving the full conjecture.