  The multi-resonance orbital model of high-frequency quasi-periodic
oscillations (HF QPOs) enables precise determination of the black hole
dimensionless spin a if observed set of oscillations demonstrates three (or
more) commensurable frequencies. The black hole spin is related to the
frequency ratio only, while its mass M is related to the frequency magnitude.
The model is applied to the triple frequency set of HF QPOs observed in Sgr A*
source with frequency ratio 3:2:1. Acceptable versions of the multi-resonance
model are determined by the restrictions on the Sgr A* supermassive black hole
mass. Among the best candidates the version of strong resonances related to the
black hole "magic" spin a=0.983 belongs. However, the version demonstrating the
best agreement with the mass restrictions predicts spin a=0.980.
