I said 10% of rides will be robotaxis and 10% of that will be in Teslas.

That is 1% of all rides taking place in Tesla robotaxis, not 10%.

Also it is about rides, not about cars. Less than 1% of cars being Tesla robotaxis is enough for 1% of rides to be Tesla robotaxi rides. A robotaxi will do multiple times more rides per day that the average car.