package operator; public class Demo01 { public static void main(String[] args) { int a=10; int b=20; int c=30; int d=40; System.out.println(a+b);//30 System.out.println(a-b);//-10 System.out.println(a*b);//200 System.out.println(a/b);//0 10/20==0.5 这个地方要取整,所以为0 向下取整; System.out.println(a/(double)b);//0.5 } }