[tex]\bf \stackrel{Permutations}{_nP_r=\cfrac{n!}{(n-r)!}}~\hspace{6em}\stackrel{\textit{22 units arranged in groups of 22}}{_{22}P_{22}=\cfrac{22!}{(22-22)!}} \implies _{22}P_{22}=\cfrac{22!}{0!} \\\\\\ _{22}P_{22}=\cfrac{22!}{1}\implies _{22}P_{22}=22!\implies _{22}P_{22}=1124000727777607680000[/tex]
