(define (double n) (+ n n))

(define (multiply n x)
  (cond
    [(>= n x) 
      (cond
        [(or (zero? x) (zero? n)) 0]
        [(even? x) (multiply (double n) (quotient x 2))]
        [(odd? x) (+ n (multiply (double n) (quotient x 2)))])]
    [else
      (cond
        [(or (zero? x) (zero? n)) 0]
        [(even? n) (multiply (double x) (quotient n 2))]
        [(odd? n) (+ x (multiply (double x) (quotient n 2)))])]))