The Hadwiger-Nelson problem asks the minimum number of colors required to color the plane such that no two points at distance 1 have the same color. It is known that this number is at least 5 [de Grey '18], and no more than 7. This market resolves to the number in question, when there is an accepted mathematical proof of its value.

If this is found to be independent of ZFC, then this resolves-to-multiple over all values that are consistent with ZFC.