On the abacus in the picture, the beads on the wires represent ones, tens,hundreds and thousands starting from the bottom wire. The picture on the right shows a modern electronic calculator. It can add,subtract, multiply and divide. It can also calculate percentages and square roots. This picture shows a computer. Computers are very powerful calculating machines. In a flash, a computer can do a calculation that you could not do in your whole lifetime Brain against computer Some people call the brain a living computer. Is a human brain a more powerful calculator than a computer? The following story may give an answer.