Hecatomb

Hecatomb: A hecatomb was a massive ancient Greek sacrifice to the gods - 100 oxen! These days it might be used metamorphically for any massacre or large scale slaughter, much like decimate that also began with a specific mathematical value in Roman times. Today heca is mostly seen as a metric prefix for 100. The metric analog to acre is hectare (100 ares) which is 10,000 square meters or 2.5 acres.

.. the day when Pythagoras first discovered [the Pythagorean Theorem], and celebrated its advent, it is said, by sacrificing a hecatomb of oxen - a method of doing honor to Science that has always seemed to me slightly exaggerated and uncalled-for.