Explanation: Start with the D on the outer left of the diagram, and move clockwise around the outer segments, then start on the N anti-clockwise around the inner segments. Letters advance through the alphabet in steps of 3, then 4, 5, and 6, repeating this sequence.
Explanation: Start with the letter J in the top left square, and move clockwise around the other squares. Letters follow the alphabetic sequence, skipping 4 letters at a time. Start with the X in the inner square in the top left, and move clockwise. These inner letters also follow the alphabetic sequence, skipping 5 letters at a time
Explanation: The diagram contains 3 sets of 4 letters - one set of outer corner letters, one set of inner corner letters, and one set of letters on each side of the square. The numerical values of the letters in each set add up to 40.