Better start saving: The price of a one-day ticket to Walt Disney World's Magic Kingdom is now $99. That's a $4 increase from the previous price hike announced in June 2013. The price hike went into effect Sunday.
Probably of Babylonian origin, an abacus is a calculating instrument that uses beads that slide along a series of wires or rods set in a frame to represent the decimal places. It is the ancestor of the modern digital calculator.
Both the abacus and the counting board are mechanical aids used for counting; they are not calculators in the sense we use the word today. The person operating the abacus performs calculations in their head and uses the abacus as a physical aid to keep track of the sums, the carrys, etc.