The greatest integer function, \(f(x) = [x]\), evaluated across the open domain boundary \(0 < x < 3\), is not differentiable at how many points?
Show Hint
The step function \(f(x) = [x]\) is always discontinuous and non-differentiable at every single integer point \(x = n \in \mathbb{Z}\). Simply count how many whole numbers fall inside the specified range.