控制数字在TEXTBOX里显示的小数位数

1.WEB.CONFIG:

 

2..CS:

precision  =  ConfigurationSettings.AppSettings[ " precision " ].ToString();
txt_SPUSD.Text = String.Format(precision,Convert.ToDecimal(COItemCostData.spUSD));
   txt_SPContract.Text = String.Format(precision,Convert.ToDecimal(COItemCostData.spContract));