Perhaps the oldest known dice were excavated as part of a backgammon-like game set at the Burnt City, an archeological site in south-eastern Iran, estimated to be from between 2800 and 2500 BCE. Bone dice from Skara Brae, Scotland have been dated to 3100 2400 BCE.

This week's Riddler Classic is a game of four-sided dice: You have four fair tetrahedral dice whose four sides are numbered 1 through 4. You play a game in which you roll them all and divide them into two groups: those whose values are unique, and those which are duplicates.