Sequential Multiplication
Jelly, 3 bytes

×’$


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How it works

×’$    Main link (or part thereof). Argument (initially input): n

 ’     Compute n - 1.
×      Multiply n by (n - 1).
  $    Combine the previous two atoms into a monadic quicklink.


Repeating the snippet n times will execute it n times, resulting in the desired output.