Abacus Mysteries that were prevalent during that time. Historically, that is the first Abacus to be used.  There used to be an initial sand tray counting device that was in use ages ago. The framed beads Abacus that is in use today came into existence after several computations and permutations done on the initial device . Today, we know  Abacus as a powerful tool for teaching arithmetic since it : Increases the understanding of the number place...