Hand Abacus (14 ч 39 мин, 21 ноя 2018 г. – 14 ч 49 мин, 1 июл 2019 г.)
Описание:
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.Добавлено на ленту времени:
Дата:
14 ч 39 мин, 21 ноя 2018 г.
14 ч 49 мин, 1 июл 2019 г.
~ 7 months