-is( _num_to_alpha(26 ** 3 + 26 ** 2 + 26 - 1 ), 'ZZZ');
-is( _num_to_alpha(26 ** 3 + 26 ** 2 + 26 ), 'AAAA');
+is( _num_to_alpha(26 ** 3 + 26 ** 2 + 26 - 1 ), 'ZZZ', 'Last triple letter return value');
+is( _num_to_alpha(26 ** 3 + 26 ** 2 + 26 ), 'AAAA', 'First quadruple letter return value');