Hand Abacus (14 h 39 min, 21 nov 2018 ans – 14 h 49 min, 1 juill. 2019 ans)
Description:
The Romans invented the hand abacus it contained several long and short grooves, and had up to five beads in each notch. The Romans developed their hand-abacus as a portable counting board-- the first portable calculating device for both engineers and businessmen.Ajouté au bande de temps:
Date:
14 h 39 min, 21 nov 2018 ans
14 h 49 min, 1 juill. 2019 ans
~ 7 months
