向上取整,再向小数点前n位取整;向下取整

1.向上取整,再向小数点前2位取整
double d = 1484.32;
int i1 =10*(int)( Math.Ceiling( d / 10));//1490//向前一位
int i2 = 100 * (int)(Math.Ceiling(d / 100));//1500向前二位
int i3 = 1000 *(int)(Math.Ceiling(d / 1000));//2000向前三位

2.向下取整
int il = (int)Math.floor(d);//1484