Question

how to write answers fastly in abacus

Answer 1

For faster calculation in abacus, the number of fingers used to move the beads plays an important role. Most widely used fingers to calculate in abacus are index and middle finger in left hand and thumb and index finger in right hand. Calculation in usually done from the middle point if you are using Soroban. Interestingly, soroban consists of odd number of rods(vertical bars).

The addition and subtraction calculations will be done from the middle point or middle rod. The key to calculate faster is to use index finger in right hand to make movements of heaven(upper) beads(both addition and subtraction), thumb for addition of earth(lower) beads and again index finger for subtraction. As for the left hand, for the movement of heaven beads, use middle finger for both addition and subtraction and for earth beads use index finger for both addition and subtraction.
Most important thing to remember while using abacus is to make movements of all of your fingers simultaneously.

EDIT:

There is also six finger technique in which thumb index and middle fingers of both hands are used. middle finger for both addition and subtraction in upper beads, index fingers for subtraction in lower beads and thumb for addition in upper beads. The six fingers technique is faster than four fingers technique