学习心得4：计算 9+99+......+9999999999(12个9)

//计算 9+99+…+9999999999(12个9)
//10^i-1
public class Test2 {

public static void main(String[] args) {
	long sum = 0;
	for (int i = 1; i <= 12; i++) {
		double s = (Math.pow(10, i) - 1); // 此函数用来计算次方函数的值
		sum += s;
		System.out.println(sum);

	}

}

}