短文填空

　　Ancient numbers

　　In ancient 　　1　　, people wrote numbers in many different 　　2　　, 　　3　　 these pictures of the number 6 show．　　4　　, they nearly all counted in the same way－in 　　5　　．

　　Zero

　　The system of numbers that nearly everyone uses today 　　6　　 of the numbers from 1 to 9 and 0 　　7　　 these ten numbers, we can write any number from the biggest to the smallest．The Indians 　　8　　 invented and developed the 1 to 9 system of numbers．They then invented the zero．This was a very important 　　9　　 because it made it easier to write big numbers and to 　　10　　．

　　Calculating machines

　　One of the first calculating machines was an 　　11　　．Abacuses are so fast and accurate that people still use them today．On the abacus in the picture, the beads on the wires 　　12　　 ones, tens, hundreds and thousands, starting from the 　　13　　 wire．

　　The picture on the right shows a modern electronic calculator．It can add, subtract, multiply and divide．It can also calculate percentages and 　　14　　 roots．

　　This picture shows a computer．Computers are very 　　15　　 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 　　16　　 computer．Is a human brain a more powerful 　　17　　 than a computer? The following story may give you an answer．

　　Shakuntala Devi is a lady from India with an 　　18　　 brain．She can calculate like lightning．In America, Shakuntala and a very powerful computer were given this problem to solve．

　　Shakuntala's brain took fifty seconds to find the answer．The computer took a minute．However, before the computer could begin 　　19　　, someone had to program it with instructions, and that took many hours．No one had to 　　20　　 Shakuntala!

1．________　2．________　3．________　4．________　5．________

6．________　7．________　8．________　9．________　10．________

11．________　12．________　13．________　14．________　15．________

16．________　17．________　18．________　19．________　20．________