//1. for循环：计算 7+77+777+…… 前10项的值 public class Homework { public static void main(String[] args) { long sum = 0; long m = 0; for (long i = 0; i < 10; i++) {
m = m * 10 + 7;
sum=m+sum;
}
System.out.println(sum); //2. for循环：计算序列的值：1,-2,3,-4,5,-6……-100 int[] oushu = new int[101]; int[] jishu = new int[101]; int sum1 = 0; for (int i = 0; i <= 100; i++) { if (i % 2 == 0) {
oushu = -i;
} else {
jishu = i;
}
sum1 = sum1 + (oushu + jishu);
}
System.out.println(sum1);
for (int j =1;j<=9;j++){ for(int i =1;i<=j;i++){
System.out.print(i+"*"+j+"="+i*j+"\t");
}
System.out.println();
}