  The equation of state of strange matter build of the u,d,s quarks in the
framework of the MIT bag model is studied. The scaling relations with bag
constant are discussed and applied to the determination of maximum frequency of
a particle in stable circular orbit around strange star. The highest QPO
frequency of 1.33 kHz observed so far is consistent with the strange stars
models for which the maximum QPO frequency is 1.7-2.4 kHz depending on the
strange quark mass and the QCD coupling constant. The linear approximation of
the equation of state is found and the parameters of this EOS are determined as
a functions of strange quark mass, QCD coupling constant and bag constant. This
approximation reproduces exact results within an error of the order of 1% and
can be used for the complete study of the properties of strange stars including
microscopic stability of strange matter and determination of the total baryon
number of the star.
