What do the numbers 1, 2, 3, 4, 5, 6, 7, 8, 9 in the Book of Changes mean?

I ching has yin and yang, three-inch three-body, four sharp and four images, five elements and five zang-organs, six rivers and seven stars, eight diagrams, nine palaces, ten heavenly stems and twelve earthly branches.

The odd-even number in the Book of Changes is "odd yang and even yin", that is, "the sky is one place and two places, the sky is three places and four places, the sky is five places and six places, the sky is seven places and eight places, and the sky is nine places and ten places".

The word "Ninth Five-Year Plan" comes from the Book of Changes. The version of the Book of Changes that has been handed down to this day is said to be played by Zhou Wenwang, so it is also called the Book of Changes. The first of the sixty-four hexagrams in the Book of Changes is the dry hexagram, which symbolizes the sky, so it becomes the image representing the emperor. Dry hexagrams are composed of six Yang hexagrams, which are extremely yang and prosperous. Count from bottom to top. Gangua is the first of the sixty-four hexagrams, so the Ninth Five-Year Plan is the first of the sixty-four hexagrams and the first of the three hundred and eighty-four hexagrams, which has become the phase of emperors. The "nine" here is not a specific number, but a symbol to distinguish the yin and yang attributes of numbers. Later, people used "Nine" and "Five" as specific figures, thinking that it was in line with the "Ninth Five-Year Plan" representing emperors. Furthermore, the use of nine or five figures in architecture is also in line with aesthetic principles.