I am trying to use a regular expression like this:

```
string Size= "10.5M";
Match m = null;
if ((m = (new Regex(@"(\d)([MGTP%]?)", RegexOptions.IgnoreCase).Match(Size))).Success)
{
    Size = m.Groups[1].ToString();
    if (m.Groups.Count > 1)
        SizeUnit = m.Groups[2].ToString(); // if not given, SizeUnit is percentage
}

```

But when I pass the value, Size shows as 10, and SizeUnit as "" instead of the expected Size = 10.5 and SizeUnit = M