.net 两个数相除计算百分比 , 保留两位小数

stringsignal="5";
decimalvalue=Convert.ToDecimal(signal)/31;
//小数据取两位
intresult=(int)(Math.Round(value,2)*100);
this.lbSingle.Text=result+"%";

decimald=(decimal)(7)/6;
value=Math.Round(d,2).ToString();

CountNum=0.0;

LeangTimeCount+=int.Parse(dsStudy.Tables[0].Rows[j]["StudyearnedTmie"].ToString());

if(LeangTimeCount==Count)
{
CountNum=1;
}
else
{
CountNum=(LeangTimeCount/Count)*100;
}

CountNum.ToString("#0.#0")+"%";