Sensible hard problems are those with an answer that can easily be verified once you know what it is but whats difficult is finding the answer. 3 - Hardest Mathematical Columbus Puzzle The Puzzle. The hardest math problems are those which remain unsolved.
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3 - Hardest Mathematical Columbus Puzzle The Puzzle. Difficulty is a subjective metric and what is difficult for some may not be difficult for others. These unsolved problems occur in multiple domains including physics computer science algebra analysis combinatorics algebraic differential discrete and Euclidean geometries graph group model. These are the NP problems that are not P problems.