epogdoon

Borrowed from Ancient Greek ἐπόγδοον (epógdoon), from ἐπι- (epi-, “greater [by]”) + ὄγδοον (ógdoon, “an eighth part”).

epogdoon (plural not attested)

1. (mathematics, Ancient Greece, rare) A number equal to another plus an eighth thereof; a number 1.125 times another.
   • 1936, Frank Cole Babbitt translating Plutarch as "Isis and Osiris" in Moralia, Vol. V, p. 103, n.:

     Eighteen... bears the epogdoon relation to sixteen, which is broken up by the intervention of seventeen, an odd number.

   • 2016, John Magee translating Calcidius as On Plato's Timaeus, p. 201:

     We cannot say that 256 is the epogdoon of 243, for in the number 256 is not contained the whole of 243 and an eighth thereof, since an eighth of 243 is approximately 30½...