Consider the standard deck of playing cards with A, 2, 3, 4, 5, 6, 7, 8, 9, 10, J, Q, K in each of four suits. If we let a joker be zero and treat the ace as one we have a 14 "digit" number system. Create a 14 by 14 grid for adding numbers in this system and write down the sums along the main diagonal. That is, what is joker+joker in this system? How about 4+4? 8+8? Etc. Fill in the entire diagonal of the table.