3 digit hexadecimal generator for Access Database

I am trying to figure out how to create a hexadecimal generator that always spits out 3 digits in C# and sends it to my access database. Here is the code that I found an example of on here and changed a little bit, but the generator sometimes only gives me 2 digits. What am I doing wrong?

Thank you,

        var r = new Random();
        int A = r.Next(100, 500);
        string hexValue1 = A.ToString("X");
        MessageBox.Show(hexValue1);