Question Number 46972 by 23kpratik last updated on 03/Nov/18
$$\boldsymbol{{let}}\:{m},{n}\:{denote}\:{any}\:{two}\:{possitive}\:{relative}\:{prime}\:{integers},{then}\:{prove}\:{that}\phi\left({mn}\right)=\phi\left({m}\right)\centerdot\phi\left({n}\right) \\ $$