What's the name of telling fortune with copper coins?

How to use copper coins to calculate divination

Fortune telling is simply to introduce 6789 from 1234. A copper coin has two sides, so we use three. After that, there are four changes before and after. The front is marked with the number "3" and the back is marked with the number "2". Add three numbers, the number range is 6789, 79 is marked with "-",and 68 is marked with "-". After six bottom-up arrangements, a hexagram was obtained. Just refer to the Book of Changes and look it up.