语句练习题9

 1         Scanner sc2 = new Scanner(System.in);
 2         System.out.print("请输入数：");
 3         int num2 = sc2.nextInt();
 4         System.out.println("请输入几个数相加：");
 5         int num3 = sc2.nextInt();
 6         int sum1 = 0;// 存储求的和
 7         for (int i = 1; i <= num3; i++) {
 8             double a = 0.0;
 9             //第n个数=第n-1个数+显示的数乘以10的n-1次方
10             for (int j = 1; j <= i; j++) {
11                 a = num2 * Math.pow(10, (j - 1)) + a;
12             }
13             System.out.println(a);
14             sum1 += a;
15         }
16         System.out.println(num3 + "个数相加的和=" + sum1);

 1         int sum2=0;
 2         for(int i=1;i<=num3;i++){
 3             int num4=0;
 4             //第n个数=第n-1个数乘以10+显示的数
 5             for(int j=1;j<=i;j++){
 6                 num4=num4*10+num2;
 7             }
 8             System.out.println(num4);
 9             sum2+=num4;
10         }
11         System.out.println(num3+"个数相加的结果="+sum2);