public class Test {
private int sum=0,num=1;
public int calSum(int maxnum){
if(num<=maxnum){
sum+=num;
num++;
calSum(maxnum);
}
return sum;
}
public static void main(String[] args) {
Test test=new Test();
System.out.println("1+2+3+...+100="+test.calSum(100));
}
}