duck

function OnGUI()
{
    var alphabet = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";

    for (var letterNum = 0; letterNum < alphabet.Length; letterNum++) {
        var thisLetter = alphabet[letterNum].ToString();
        var buttonRow = letterNum / 8;  // it's an int, so will be rounded down
        var buttonX = 100 + ((letterNum % 8) * 40);
        var buttonY = 50 + (buttonRow * 40);
        if(GUI.Button(Rect (buttonX,buttonY,50,50), thisLetter)){
            // the test here!
        }
    }
}