PRINT "The known factorial of 34 is 2.952328e+038"
PRINT "The calculated factorial of 34 is ";Factorial!(34)

FUNCTION Factorial! (R!)
  IF (R! > 0) AND (R! <= 34) THEN
    FUNCTION = R! * Factorial!(R!-1)
  ELSE
    FUNCTION = 1
  END IF
END FUNCTION

Result:

The known factorial of 34 is 2.952328e+038
The calculated factorial of 34 is  2.952328E+38