Why is nine the pole number of yang number? What is the number of poles?

1, in Zhouyi, six is yin, nine is yang, and nine is the extreme number because of decimal system.

2. The river chart has 10 numbers: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10. Where 1, 3, 5, 7, 9 is Yang; 2, 4, 6, 8, 10 is negative.