Converting the Old Babylonian Tablet ‘Plimpton 322’ into the Decimal System as a Classroom Exercise

For didactic purposes, we present a construction method for a decimal analogue of the Old Babylonian tablet Plimpton 322, produced by performing operations in base 10 (rather than in base 60), and designed so that all rational numbers are decimal fractions. This construction provides a nice classroom activity for prospective K–12 mathematics teachers, as well as high school students. The activity allows the participants to experience mathematics from the Old Babylonian period while remaining in the comfort zone of base 10. Working in a group through the interesting arithmetic algorithm behind the construction also consolidates several notions related to numbers and numeration systems, while providing opportunities to make and test mathematical conjectures. Last but not least, the activity allows the participants to better understand Plimpton 322 itself.

We also present historical and mathematical overviews of Plimpton 322 and offer practical suggestions for using the activity in the classroom. The activity itself can be downloaded by clicking here.