/**

 * 用do-while计算1+1/2！+1/3！+……的前20项的和

 * @Hoagn

 *

 */

public class Add2 {

	public static void main(String[] args) {

		int  i = 1, a = 1;

		double sum = 0,b = 0;

		do {

			a = i * a;

			b = 1.0 / a;

			sum = sum + b;

			i++;

		}while(i <= 20);

		System.out.println(sum);

	}

}

/**

 * 用for循环计算1+1/2！+1/3！+……的前20项的和

 * @author Hogan

 *

 */

public class Add1 {

    public static void main(String[] args) {

        int  i = 1, a = 1;

        double sum = 0,b = 0;

        for(i = 1; i <= 20; i++) {

            a = i * a;

            b = 1.0 / a;

            sum = sum + b;

        }

        System.out.println(sum);

    }

}

public class HomeWork05 {

    public static void main(String[] args){

        {

            int i,j,k;

            for(i=1;i<1000;i++)

            {

                int sum=0;

                for(j=1;j<i;j++)

                {

                    if(i%j==0){

                        sum+=j;

                    }

                }

                    if(sum==i){

                    System.out.println(i);

                }

            }

        }

    }

}

public class demo49_4_5 {

	public static void main(String[] args) {

		long sum=0,item=8;

		for(int i=1;i<=10;i++) {

			sum = sum+item;

			item = item*10+8;

		}

		System.out.println(sum);

	}

}

public class Main {

    public static void main(String args[]) {

        int i=1,s=0;

        while(s<8888){

            i++;

            s+=i;

        }

        System.out.println(i);

    }

}

 public class Hello {

     public static void main(String[] args) {

         int sum=0;

         int i;

         for(i=1;sum+i<8888;i++) {

             sum=sum+i;

         }

         System.out.println("sum为："+sum);

         System.out.println("最大正整数为："+(i-1));

     }

 }