9B students inscribing operations into clay tablets using four different based number systems.

The boys have been learning about the first known number system in use in human history - Sexagesimal, base 60 used by the Sumerians in the area around modern day Iraq (about 4000 to 6000 years ago). 

This requires 60 different symbols for the numbers 0 to 59. This ancient civilisation used clay dug out from the banks of the Tigris and Euphrates rivers. The boys then repeated their operations using binary (Base 2 - vital for operations of computers), followed by our very familiar decimal system (Base 10) and finally a base system the boys made up themselves.