The abacus is an ancient calculating tool. Simple rules for counting on an abacus are described here.
Step 1: Place the abacus on a flat surface Place the abacus on a flat surface with the upper section away from you. Push all the beads in the upper and lower sections away from the central crossbar.
TIP: The Chinese abacus has 13 columns of counting beads divided into an upper and lower section by a horizontal crossbeam. Each column of the upper section contains two beads, and each column in the lower section five beads.
Step 2: Move the beads to count Move the corresponding number of beads on the right-most lower deck column toward the central crossbeam to count from one to five.
TIP: Each bead in the right-most upper deck column has a value of five.
Step 3: Carry over the beads as needed Set the 5-bead above the crossbeam in the same column when you have five beads in the lower section and need to add one more. Then clear the five beads in the lower section.
Step 4: Continue carrying over the beads Set a second 5-bead in the same column when you have five more beads set in the lower section and need to add one more. The two beads in the upper section correspond to the number 10. Clear the five beads in the lower section.
Step 5: Use columns to the left as needed Continue counting in the same manner using columns to the left to represent numbers of increasing value. From right to left, the first vertical column represents units, the next represent 10s, then 100s, and so on.
FACT: In 1946 a Japanese abacist outperformed an electric calculating machine using a Japanese-style abacus.