This paper demonstrates that transfer function zeros are equal to the poles of a new inverse system, which is valid even for the strictly proper case. This is a new finding, which is important from practical as well as theoretical viewpoints. Hence, the dominant zeros can be computed as the dominant poles of the inverse transfer function by the recent efficient SADPA and SAMDP algorithms, which are applicable to large-scale systems as well. The importance of computing dominant zeros and the performance of the algorithms are illustrated by examples from large practical power system models. These examples constitute new practical uses for single-input single-output (SISO) and multi-input multi-output (MIMO) zeros, which may be of benefit to power system simulation studies and field tests related to oscillation damping control.