How did Zhouyi's fortune-telling work out what divination he was?

Fortune telling in Zhouyi is not as simple as you think.

For example, some of you use Ziwei, some use Qimen, some use eight characters, some use six hexagrams, and so on, but all the methods belong to the sect.

What do you want from yourself? It is based on your date of birth. When you add it up and divide it by 8, the remainder hangs up. You can use Kun to hang it up and down if you divide it. If you divide them, more than eight can be hung down. You can hang it with Kun if you split it. If you separate it, you can move it by 6.