To use an abacus, first assign the beads that are below the horizontal bar a value of one, and then assign the beads that are above the horizontal bar a value of five. Assign each vertical bar with a place value. Perform the mathematical operation by starting with the original number and working through each place value from left to right.
- Assign the correct value to the beads above and below the horizontal line
The beads above the horizontal line are worth five units; the beads below are worth one unit.
- Assign place values to each vertical bar
Begin with the vertical bar at the very right of the abacus, and assign this bar the ones place value. Move on to the vertical bar immediately to the left, and assign it the tens place value. Continue this process by assigning each bar to the left of the previous bar an increased multiple of 10.
- Perform the mathematical operation
Enter the first number in the abacus. For example, if your first number is 100, find the vertical bar that represents the 100's place and move one bead up to the horizontal bar. Take the second number, and perform the operation for each place value separately, starting from the highest to lowest. For example, if you want to add 221 to 100, start by adding two and one. Three beads are now in the vertical bar representing the hundreds place value. Continue to the operations vertical bars representing the tens and the ones place values. Read the final figure from the abacus.