实用法宝
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：
Shakuntala Devi is a lady from India with an amazing brain ．She can calculate like lightning ．In
America，Shakuntala and a very powerful computer were given this problem to solve．
☆Find the number that, when it is multiplied 23 times by itself, *gives.this.answer:9167486769200391580986609275853801624831066801443086 2240712651642793465704086709659327920576748080679002
2783016354924852380335745316935111903596577547340075
681688305620821016129132845546805780158806771
Shakuntala's brain took fifty seconds to find the answer. The computer took a minute．However, before the computer could begin calculating，someone had to program it with instructions，and that took many hours ．No one had to program Shakuntala！
Use your own living computer to solve the problem above ．If it is not powerful enough，you will find the answer on page 59．
数字：每个人的语言
你会多少种语言？每个人至少会两种—他或她的母语和国际数字语言。 古代数字
在古代，人们用各种各样的方法记录数字，就像这些图片所表示的数字6一样。但是，他们几乎都用一种方法数数—十进制。
零
当今几乎每个人都在使用的数字系统由数字1到9和零组成。用这十个数字，我们可以写出从最大到最小的任何一个数字。印度人最早发明并发展了1到9这个数字系统。他们接着又发明了零。这是一项重要的发明，因为它使书写大数目和计算更容易。
计算器
算盘是最早的计算器之一。算盘计茸很快并且很准确，因此人们至今仍在使用。图片中的算盘，从下面开始，杆上的珠子依次代表个位、十位、百位、千位。 右边的图片展示的是一个现代的电子计算器。它能做加、减、乘、除各种运算。它还能算百分数和平方根。
这幅图片展示的是计算机。计算机是非常强大的计算机器。在一瞬间，计算机所做的计算是你一生都做不完的。
大脑对电脑
有些人把大脑叫做活电脑。人的大脑是比电脑还更强大的计算器吗？下面的故事将给出一个答案。
Shakuntala Devi是一个长着令人吃惊的大脑的印度妥人。侧的计算很快。在美