... pulverem," (de nat. Deorum, ii.18). Tertullian calls a teacher of arithmetic "primus numerorum arenarius" (de Pallio, in fine). The counters were made of various materials, ivory principally, "Adeo nulla uncia nobis est eboris, etc." (Juv. XI. 131), sometimes of precious metals, "Pro calculis albis et nigris aureos argenteosque habebat denarios" ... — The Earliest Arithmetics in English • Anonymous
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