rewrite (S_pred m 0); trivial with arith.
simpl in |- *; auto with arith.
Qed.
Hint Resolve le_mult_l.

(* Specifications: *)
Lemma le_mult_r : forall n m : nat, 0 < m -> n <= n * m.
intros n m; elim (mult_comm m n); auto with arith.