insider.si.edu6 个月
The Abacus and the Numeral Frame
The abacus is a computing device on which arithmetic calculations are performed by sliding counters (beads, pebbles, or flat discs) along rods, wires or lines. The instrument may have originated in ...
insider.si.edu5 个月
The Abacus and the Numeral Frame
The abacus is a computing device on which arithmetic calculations are performed by sliding counters (beads, pebbles, or flat discs) along rods, wires or lines. The instrument may have originated in ...