There are two thematic items that I see as not being (physically) a part of the description of the theme, which I think is 3, 8, 4, as mentioned earlier in the thread . Of these I have used the four-letter one that is (again physically) within the description of the theme. When I follow the instructions I end up with a letter that seems completely random. I'm not great at maths but this is simple arithmetic and I can't see that I have gone wrong. So is the reasoning of my choice above wrong?