The abacus, also called a counting frame, is a calculating tool that was in use in Europe, China and Russia. Abaci are often constructed as a bamboo frame with beads sliding on wires, but originally they were beans or stones moved in grooves in sand or on tablets of wood, stone, or metal. In abacus, there are numerous different methods to perform a certain type of calculation, like addition and multiplication, or even more complex ones, such as calculating square roots.
Abaci come in different designs. Some designs, like the bead frame consisting of beads divided into tens, are used mainly to teach arithmetic, although they remain popular in the post-Soviet states as a tool. Many use calculators and computers instead of abaci to calculate, abaci still remain in common use in some countries. Some people who are unable to use a calculator because of visual impairment may use an abacus.
Around the world, abaci have been used in pre-schools and elementary schools as an aid in teaching the numeral system and arithmetic. The wire frame may be used either with positional notation like other abaci or each bead may represent one unit. The red-and-white abacus is used in contemporary primary schools for a wide range of number-related lessons.