Abacus is latin word that has its orgin in the greek word abax or abakon ( meaning “ table or tablet”) which in turn possibly originated from the semitic word abq meaning : sand” The abacus is one of may counting devices invented to help count large numbers. The abacus is a device usually of wood ( plastic in recent times) having a frame that hold rods with freely sliding beads mounted on them. The person operating the abacus performs  calculation mentally and uses the abacus as a physical aid to keep tract of the calculation.

Components of Abacus
 

 

Abacus is a frame dived in two parts through horizontal bar, which separates the frame into two parts known as “upper deck and “ lower deck”. It has a series of vertical rods having beads freely sliding on them. The value of upper deck beads are 5 and lower deck beads are 1 each on unit place.

Application of Abacus
Suppose we have to add 4 and 5 get 9 , then add 4 lower beads ( i.e 4 lower beads upwards such that they touch the bar) and add 5 ( i.e move upper bead downwards such that it touches the bar) at unit place. Hence we get 9 on Abacus.