项目一----整数和。偶数和。阶乘和。

public class Sumn {
public static void main(String args[]){
	System.out.println("整数和");
	Sum s1=new Sum();
	s1.print();
	System.out.println("偶数和");
	Sumn1 s2=new Sumn1();
	s2.print();
	System.out.println("阶乘和");
	Sumn2 s3=new Sumn2();
	s3.print();
} 
}


public class Sum {
int sum=0;
int n;
 public int sum(int n){
	int x=0;
	for(int i=1;i<=n;i++){
		x=x+i;
	}
    int s=x;
	return s;
}
public void print(){
	System.out.println(sum(10));
}
}



public class Sumn1 {
int sumn=0;
int n;
public int sumn(int n){
	int x=0;
		for(int i=2;i<=n;i=i+2){
			x=x+i;
		}
	    int s=x;
		return s;
	}
	public void print(){
		System.out.println(sumn(10));
	}
	}



public class Sumn2 {
	
	 public int sumn2(int n){
		int x=1;
		for(int i=1;i<=n;i++){
			x=x*i;
		}
	    int s=x;
		return s;
	}
	public void print(){
		System.out.println(sumn2(10));
	}
	}