The Abacus
Many sums were performed on paper in a long and laborious manner as this was the usual way to do calculations before the invention of calculators and computers. The abacus, which had originated in the East in ancient times, was often used as an aid to calculations. Each row of beads represented a number, and the next row represented a multiple of the number. So if the first row was one to ten, as a count was being performed a bead would be moved from left to right, until nine beads had been moved to the right hand side, and for the next item to be counted the nine beads were returned to the left hand side, and one bead on the second row moved to the right, represented one 10.

 

Victorian abacus

The Victorian Abacus