How to allow numbers and decimal points ?

Question

if (!int.TryParse(ds.Tables[s].Rows[i][Columncountvalue + 10].ToString().Trim(), out parsedValue))  
{ 
//statement 
}
I have used above code for restrict enter letters in data table  columns.now i want to allow decimal points and numbers in data table  (100, 102.25)
 How to do it.