Since we have 10 fingers on our hands, it makes sense that we adopted a base-10 number system. But there is nothing unique about the number 10. In fact, any number can be used as the base of a positional number system. The simplest possible system is the base-2 system, also called binary numbers. The binary system is used by computers.
Students can explore number systems with different bases using the Number Systems Gizmo. In the Gizmo, students choose the base (up to 10) and then add beads to a tray to represent numbers in that base. The base determines how many beads can be added to each column of the tray.