It is better if the situation on ground is represented by an exponential equation.
This is because, since we have the number of teams reducing by exactly half at every playoff round, this means that we have a base of 2 which can be raised to a negative power since we are talking about a decrease.
We can then place the number of rounds as an adjoining power to what the two is raised and this easily will get us the number of teams which is eventually decreased at every point of the playoffs
