What is the formula of abacus calculation?

One up one, two up two, three up three, four up four, five up five, six up six, seven up seven, eight up eight, nine up nine.

One drops five to four (4+ 1), two drops five to three (3+2, 4+2), three drops five to two (2+3, 3+3, 4+3) and four drops five to one (1+4, 2+4, 3+4).

Six on one to five into one (5, 6, 7, 8+6), seven on two to five into one (5, 6, 7+7), eight on three to five into one (5, 6+8) and nine on four to five into one (5+9).

Commonly used terms

Neutral: when both the upper and lower gears of a certain gear are off the beam, it is called neutral. Neutral means this gear doesn't count, or it means 0.

Empty disk: All gears of the abacus are in neutral, that is to say, there is no counting at all. This is called empty disk.

Inner beads: The counting beads counted by the light beam are called inner beads.

Outer beads: Counting beads that are not counted from the light beam are called outer beads.

Pull up: refers to pulling up the lower bead against the beam.

Pull: refers to pulling the upper bead towards the beam.

Pull out: refers to pulling the upper bead or the lower bead away from the beam.