Split the left and right hand circles in half vertically. The letter with the numerical value of the sum of the digits in the left half of the left hand circle is placed in the top left segment of the central circle, and the letter with the numerical value of the sum of the digits in the right half of the left hand circle is placed in the top right segment of the central circle. Repeat this formula for the 2 halves of the right hand circle, putting the resulting letters in the lower segments of the central circle.
In each row, add together the numerical values of the 3 central letters to give a 2 digit sum, and put this 2 digit sum in the left and right hand boxes at the end of the rows.
In each circle, multiply the inverse alphabetical value of the upper left hand letter by the regular alphabetical value of the upper right hand letter to give the value in the lower segment.
Splitting the diagram in half both horizontally and vertically, each quarter contains a pattern of black squares, representing the letters W, X, Y and Z.