Below is a form that can help you convert between bytes (8-bit binary numbers) and decimal easily. Feel free to play with it.
The form works this way: if you enter a number in the decimal field and press the tab key (on your keyboard), you'll see the binary representation as a series of checked squares (1) and unchecked squares (0). Vice-versa, by checking the boxes in the binary row, you see the decimal number changing automatically.
Of course, you know that you cannot go over 255. Why is that?