按钮“第一题”：计算1-1/2+1/3-1/4+……+1/99-1/100

按钮“第二题”：计算1!+2!+……+10!

按钮“第三题”：从键盘上输入任意10个数，统计出其中负数的个数。

按钮“第四题”：假设我国1999年有人口12.4亿，年增长率为1 ，编写程序，计算哪一年人口增加到18亿。

-Button " first question" : Calculate 1-1/2+1/3-1/4+ ......+1/99-1/100 button " second question" : Calculation 1+2+ ......+10 Button " third question!!! " : Enter any 10 numbers from the keyboard, the statistics of which a negative number. Button " Fourth Question" : the assumption of 1999 had a population of 1.24 billion, an annual growth rate of 1 , the preparation process, which is calculated population increased to 1.8 billion a year.