Question

编写一个JAVA应用程序，使用for循环计算8+88+888+8888+88888+...的前十项和

Answer 1

int sum = 0;

for (int i = 1; i <= 10; i++) {
String join = "";
for (int j = 1; j <= i; j++) {
join += "8";
}
sum += Integer.valueOf(join);
System.out.println(sum);
}

Answer 2

public class Test {
public static void main(String[] args) {
String a="";
long b;
int sum=0;
for(int i=0;i<10;i++){
a+="8";
b=Long.parseLong(a);
sum+=b;
System.out.println("结果为"+sum);
}
}
}