diff --git a/lib/range_math.rb b/lib/range_math.rb
index da68ff3..996aa81 100644
--- a/lib/range_math.rb
+++ b/lib/range_math.rb
@@ -50,6 +50,8 @@ class Range
     end
   end
 
+  private
+  
   def pair_or_num operator, other
     if other.is_a? Range
       calc_pairs operator, other