\global\def\sgn{\mathop{\rm sgn}}\eqalign{(\cos 0+\cos 0+\cos 0)! =& 6\cr
(1 + 1 + 1)! =& 6\cr
\varphi(4)+\varphi(4)+\varphi(4) =&6&,\qquad \varphi(x) \hbox{ je {\it Ojlerova} funkcija}\cr
4+\sgn 4+\sgn 4 =& 6\cr
8-\sgn 8-\sgn 8 =&6\cr
\varphi(9)+9-9=&6\cr
\sqrt{9}+\sqrt{9}\cdot\sgn 9=&6\cr}