You are right, the terms A7, A8, A9 originally come from the jargon of the real estate speculation circle, used to indicate the scale of individuals or assets. The specific meanings are:
A7 = One million (1,000,000)
A8 = Ten million (10,000,000)
A9 = One hundred million (100,000,000)
A10 = One billion (1,000,000,000)
A11 = Ten billion (10,000,000,000)
A12 = One hundred billion (100,000,000,000)
In addition to these, the notation A7.3 indicates a more precise amount, for example, A7.3 represents three million.
These "asset levels" are typically used to quickly understand someone's wealth level within the circle. As wealth accumulates, the A level increases, and many people regard this as a symbol of status and wealth.
As for friends at A12, there are indeed quite a few – after all, in modern society, many large entrepreneurs and investors have already accumulated assets at the hundred billion level. So, on the street, there may really be several friends at A12.
