((((n/E)))^n)(Sqrt[2π n])  < n! < ((((n/E)))^n)(Sqrt[2π n])(1 + (1/(11n)))

Plot[Tooltip[{((((n/E)))^n)(Sqrt[2π n]),n!,Gamma[n+1],((((n/E)))^n)(Sqrt[2π n])(1 + (1/(11n)))}], {n, 1, 4}]

Plot[Tooltip[(n)!], {n, 1, 4}]