11，含不同数字的三位数：

public class ThridNum {
    public static void main(String[] args) {
        int count = 0;
        for (int x = 1; x < 5; x++) {
            for (int y = 1; y < 5; y++) {
                for (int z = 1; z < 5; z++) {
                    if (x != y && y != z && x != z) {
                        count++;
                        System.out.println(x * 100 + y * 10 + z);
                    }
                }
            }
        }
        System.out.println("All have " + count + " thrrir numbers.");
    }
}

12，求奖金数：

import java.util.Scanner;

public class Bonus {
    public static void main(String[] args) {
        System.out.println("Please input the gain this year: ");
        Scanner scanner = new Scanner(System.in);
        int Gain = scanner.nextInt();
        int Bonus;
        if (Gain <= 100000) {
            Bonus=(int) (Gain * 0.1);
            System.out.println("The bonus is: " +Bonus );
        } else if (Gain <= 200000) {
            Bonus=(int)(10000 + (Gain - 100000)    * 0.075);
            System.out.println("The bonus is: " + Bonus);
        } else if (Gain <= 400000) {
            Bonus=(int)(10000 + 7500+ (Gain - 200000) * 0.05);
            System.out.println("The bonus is: " + Bonus);
        } else if (Gain <= 600000) {
            Bonus=(int)(10000 + 7500 + 10000+ (Gain - 400000) * 0.03);
            System.out.println("The bonus is: " + Bonus);
        } else if (Gain <= 1000000) {
            Bonus=(int)(10000 + 7500 + 10000 + 6000+ (Gain - 600000) * 0.015);
            System.out.println("The bonus is: " + Bonus);
        } else {
            Bonus=(int)(10000 + 7500 + 10000 + 6000+ 6000 + (Gain - 1000000) * 0.01);
            System.out.println("The bonus is: " + Bonus);
        }
    }
}

13，求100000内的完全平方数：

public class FullSquareNum {
    public static void main(String[] args) {
        for (int i = 0; i < 100000; i++) {

//一个数的平方根如果是个整数，则该数是完全平方数
            if (Math.sqrt(i + 100) % 1 == 0 && Math.sqrt(i + 268) % 1 == 0) {
                System.out.println(i + " IS FULL SQURE NUMBER.");
            }
        }
    }
}

11～15