diff --git a/lib/decisiontree/id3_tree.rb b/lib/decisiontree/id3_tree.rb
index 0e8aaa7..8221962 100755
--- a/lib/decisiontree/id3_tree.rb
+++ b/lib/decisiontree/id3_tree.rb
@@ -127,12 +127,12 @@ module DecisionTree
       index = attributes.index(attribute)
 
       values = data.map { |row| row[index] }.uniq
-      remainder = values.sort.inject(0, :+) do |val|
+      remainder = values.sort.inject(0) do |sum, val|
         classification = data.each_with_object([]) do |row, result|
           result << row.last if row[index] == val
         end
 
-        ((classification.size.to_f / data.size) * classification.entropy)
+        sum + ((classification.size.to_f / data.size) * classification.entropy)
       end
 
       [data.classification.entropy - remainder, index]