It’s one of those hidden-in-plain-sight rules of life: the opposite faces of standard dice always sum to seven. Six is opposite one; five is opposite two; three is opposite four. It’s just how ...

Problem 3 is all about different nets close netA 2-D plan made up of the faces of a 3-D object. This can be folded to form the 3-D object. and working out which ones can fold into cubes or dice.