39. Which of the following is still useful for adding numbers? A. EDSAC B. ENIAC C. Abacus D. UNIVAC E. None of the above
Abacus : An abacus is a manual aid to calculating that consists of beads or disks that can be moved up and down on a series of sticks or strings within a usually wooden frame. The abacus itself doesn't calculate; it's simply a device for helping a human being to calculate by remembering what has been counted.
