Convert Hexadecimal to Decimal

public string HexaToDecmialConversion(string hexvalue)
{
 string decmialValue = "";
 for(int i=0; i<hexvalue.Length; i+=2)
 {
  string hex = hexvalue.Substring(i,2);
  decmialValue += Int32.Parse  
  (hex,System.Globalization.NumberStyles.AllowHexSpecifier).ToString();
 } 
 return decmialValue;
}