What are some unsolved problems in math which seem easy at first glance?

Here's a good one that's slightly less well known: if 2x and 3x are both integers, must x be an integer as well?

(This is known to be the case if you also assume that 5x is an integer, but that's an extremely difficult theorem.)

Oh, and here's another: can you color the points of the plane in 4 colors so that no two points 1m apart have the same color? How about 5 colors? 6?

(With 3, you definitely can't (cool puzzle). With 7, you definitely can (slightly less cool puzzle). Nobody knows what the minimum number of colors is).


please share if you like it 

Comments

Popular posts from this blog

Solve Dis Riddles