Hand Abacus (14h 39min, nov 21, 2018 y – 14h 49min, jul 1, 2019 y)
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.Added to timeline:
Date:
14h 39min, nov 21, 2018 y
14h 49min, jul 1, 2019 y
~ 7 months