Gann himself is very proficient in mathematics. Gann himself invented a magical chart called Nine palace map, which is one of many Gann calculators. The following figure

There is a magical diagonal line on this picture. The upper number of this line is the square of 1- 19, with odd squares on one side and even squares on the other. The square of 9 and 12 is on this line. 9 is the largest composite number in 10, and the square of 12 is 144, which is an important number in Fibonacci sequence. So he attaches great importance to these two figures. In fact, he attaches great importance to all the figures on this line.