Abacus Basic Use and Introduction to Counting
This video is an introduction to soroban construction and some of its basic use. Here we have a 17 rod soroban. I can represent a base-10 number up to 17 digits. The soroban is constructed with 17 vertical rods each rod containing 5 beads. The beads are separated by a counting bar call the reckoning bar. The single bead above the bar is called the Heavenly bead and has a value of 5. The four beads below the bar are called Earthly beads and each have a value of 1. For a bead to be counted, the bead must be touching the reckoning bar directly or indirectly through another bead.
To begin using the abacus we must first learn how to hold the abacus and initialize all the rods to a zero value. For right-handed people, we hold the abacus on the left side with our left index finger and thumb. We move the beads with our right hand index finger and thumb. During abacus use, the left hand continuously holds the abacus to prevent loss of a calculation by accidentally moving beads. For calculations we use our right hand thumb to move lower beads up to the bar and our right hand index finger to move lower beads away from the bar. The upper 5 bead is moved to and away from the bar by the index finger. To begin a calculation we must set all the abacus rods to zero by first tilting the abacus up towards you at a 45 degree angle so all the beads fall to their bottom position. Tilt the abacus by only lifting the top of the abacus and maintaining the bottom of the abacus in contact with your working surface, i.e. a desk. After all the beads have fallen to the bottom we gently lay the abacus down flat again. Next we take our right hand index finger starting from the left side of the abacus and run our index finger from left to right pushing all the heavenly beads away from the reckoning bar. This initializes all the rods to a value of zero to begin a calculation.
Now let’s learn to do simple counting from 0 to 9 on the abacus. To represent 1 on the abacus, we add 1 by moving 1 lower bead to the bar with our thumb. To add the numbers 2, 3, and 4 we simply move the corresponding number of lower beads to the bar with our thumb. To add 5 just move the upper heavenly bead to the bar with your index finger. To represent the number 6 on the abacus we grab both the upper 5 bead and 1 lower bead at the same time pinching both beads to the bar with our index finger and thumb. The number 7 would be the upper 5 bead with 2 lower beads. The number 8 is the upper 5 bead with 3 lower beads. And finally represent the number 9 by pinching all the beads on the rod to the bar.
A good way to practice counting on the abacus is to sequence through all 10 digits starting from zero. First add 1 and then subtract 1 from the abacus remembering to use the thumb to add and the index finger to subtract the bead. Next add and subtract 2. Continuing doing the addition and subtraction of the same number 3, 4, 5, 6, 7, 8, and 9. Always practice counting with the correct finger movements and you will be amazed how fast you become in a short period of time.