Why is Xiaomi No.9 balance car called No.9?

Because robot No.9 is the name of a balance car, which belongs to Nainbo Company. Later, Xiaomi invested in Nainbo Company, and then Nainbo Company produced a new product, namely Robot 9. There is more than one robot No.9, but in order to show that it is a company invested by Xiaomi and to take advantage of Xiaomi's reputation, it is also called Xiaomi Balance Car.