MATHEMATICIAN

Life
Aethra was the daughter of Pittheus, king of Troezen, the wife of Aegeus, king of Athens, and the mother of Theseus. She is cited by Homer, Menagius, Strabo, Pausanias and Plutarch.

She taught arithmetic (reckoning) to the children of Troezen, using the Cretan/Mycenaean system which remained in use until the 6th century BC. This system was extremely complicated, as each symbol had to be repeated many times and the number zero had not yet been invented. She also taught her pupils the use of the abacus, the world's first calculating device. This was a board measuring 20 x 30 cm, marked with lines at regular intervals and equipped with counters whose positions indicated numerical values - i.e. ones, tens, hundreds, and so on. Moving the counters to the right marked an increase in value, to the left a decrease.