#!/usr/bin/tcl

proc fak_rek n { 
     if {$n <= 1} { 
          return $n 
     } else {
 		  return [expr $n*[fak_rek [expr $n-1]]]
     }
}

proc timing niter {
	return [expr {[lindex [time {
		for {set n 0} {$n < $niter} {incr n} {set x [fak_rek 12]}}] 0] / $niter}]
}


puts [timing 1000]