;; arith.txt

;; --- + ---

(+ 1 2 3)
=> 6
(+)
=> 0
(+ 2)
=> 2

;; --- - ---

(- 3)
=> -3
(- 3 4)
=> -1
(- 0 3 7)
=> -10

;(* 1 2)
;=> 2