There are three forms of the abacus used today. They are primarily used in China, Russia and Japan. These counting devices were first constructed thousands of years ago out of rectangular frames made of metal, wood or stone and were used to string beads onto vertical wires. Scholars disagree as to who invented the abacus first, but most determine that it was the Chinese who introduced the abacus to both Russia and Japan, though there are abacus variations in both those countries. Typically, the abacus has 13 vertical wires with seven beads on each wire. Usually, a horizontal divider separates the seven beads with two above the divider, and five beads below it on each separate vertical wire.
To make an abacus suitable for use by a beginning math student, you will need a pencil, nine unused popsicle sticks, 56 large pony beads or beads with large holes, eight 4-inch bamboo skewers and wood glue. First, lay down three popsicle sticks parallel to each other. Then, use the pencil to draw eight lines that are evenly spaced and centered across the sticks. Take the bamboo skewers and place them where you made the pencil marks, making sure there are two popsicle sticks at each end and the middle stick is at least 1 inch away from the other two. Thread the bamboo skewers with seven beads. Glue a thin line on the pencil marks, and place the skewers on the glue. Make sure to keep the beads divided, and let the glue dry. Glue three popsicle sticks on top of the other ones and let dry. You may need to add more popsicle sticks to allow the beads to glide smoothly across the bamboo skewers.
To use an abacus properly, keep in mind that each bead represents a unit of measure. You get to decide what that measure is, so one bead could represent 5 units or it could represent a single unit, depending on how high you wish for your child or student to count. Each vertical wire is a "column," such as tens, hundreds, thousands, etc., and you read the amounts left to right. For example, you could set the top half of your abacus to units of 5 each, and the bottom to single units. So if you wanted to make the number 9, you would push one bead from the top half of the abacus toward the divider, and four beads from the bottom half toward the divider to add up to nine.
Doing simple math on the abacus isn't difficult, once students get the grasp of reading the instrument and its designated units. To add, subtract, multiply or divide, move from right to left on the abacus, just as you would if you were doing a math sum on paper. For example, say you want to add 53 to 34. Start with four beads pushed up from the lower half on the single units column, and three beads pushed up from the lower half of the abacus in the tens column. Then, to add three to the first units column, push down one bead from the top half, and push up two beads from the bottom half. That essentially adds three units, making the first column total seven. Repeat the same method with the tens column: push down one bead from the top to add 50 units to the tens column. Your total in the tens column, including the three beads already pushed up from the bottom half, should be 80, for a sum of 87.