1. n! = 1*2*3*4....*n,计算2！，4！，6！，8！和10！，显示计算结果

public class Base03 {
    public int fun(int n){
        int m = 1;
        for (int i=1;i<=n;i++){
            m = m * i;
        }
        return m;
    }
    public static void main(String args[]){
        Base03 bs = new Base03();
        System.out.println("2! = "+ bs.fun(2));
        System.out.println("4! = "+ bs.fun(4));
        System.out.println("6! = "+ bs.fun(6));
        System.out.println("8! = "+ bs.fun(8));
        System.out.println("10! = "+ bs.fun(10));

    }
}

2.请写出使用for语句计算 S = 1 + 1/2 + 1/3 + ···+ 1/n 的代码

public class Base04 {
    public double fun(int n){
        double S=0;
        for (int i=1;i<=n;i++){
            S = S + 1.0/i;
        }
        return S;
    }
    public static void main(String args[]){

        Base04 bs = new Base04();

        System.out.println("n=5 S="+bs.fun(5));
        System.out.println("n=10 S="+bs.fun(10));
        System.out.println("n=100 S="+bs.fun(100));

    }
}

3.计算 1 + 1/3 + 1/6+···+ 1/3*n 的值

public class Base05 {
    public double fun01(int n){
        double S1=1.0;
        for (int i=1;i<=n;i++){
            S1 = S1 + 1.0/(3*i);
        }
        return S1;
    }
    public static void main(String args[]){
        Base05 bs1 = new Base05();
        System.out.println("1+1/3+1/6+...+1/3*5 = "+bs1.fun01(5));
        System.out.println("1+1/3+1/6+...+1/3*10 = "+bs1.fun01(10));

    }
}

4.打印下面的图案

* * * * * * *
  * * * * *
    * * *
      *
    * * *
  * * * * *
* * * * * * *

public class Base06 {

    public static void main(String args[]){
        for (int i=-3 ;i<4;i++){
            for (int k = 6-Math.abs(2*i);k>0;k--){
                System.out.print(" ");
            }
            for (int j=1;j<=Math.abs(2*i)+1;j++){
                System.out.print("* ");
            }
            System.out.print("\n");

        }
    }
}

5.打印下面图案 （10 * 10）

*  *  *  *  *  *  *  *  *  *
*  *  *  *  *  *  *  *  *
*  *  *  *  *  *  *  *
*  *  *  *  *  *  *
*  *  *  *  *  *
*  *  *  *  *
*  *  *  *
*  *  *
*  *
*

public class Base07 {
    public static void main(String args[]){
        for(int i=0;i<10;i++){
            for(int j=1;j<=10-i;j++){
                System.out.print("*  ");
            }
            System.out.print("\n");
        }
    }
}

6.打印九九乘法表   

public class Base08 {
    public static void main(String args[]){
        for(int i=1;i<=9;i++){
            for(int j=1;j<=i;j++){
                int c = i*j;
                System.out.print(j+"*"+i+"="+c+" ");
            }
            System.out.print("\n");
        }
    }
}