diff --git a/lib/binary_to_decimal.rb b/lib/binary_to_decimal.rb
index 439e8c6..3eef7f4 100644
--- a/lib/binary_to_decimal.rb
+++ b/lib/binary_to_decimal.rb
@@ -5,5 +5,27 @@
 # Calculate  and return the decimal value for this binary number using
 # the algorithm you devised in class.
 def binary_to_decimal(binary_array)
-  raise NotImplementedError
+  sum = 0
+  exponent = 7
+  index = 0
+  8.times do
+    if binary_array[index] == 1
+      sum += (2 ** exponent)
+    end
+    exponent -= 1
+    index += 1
+  end
+  return sum
 end
+
+#improved verision:
+def binary_to_decimal(binary_array)
+  sum = 0
+  8.times do |index|
+    if binary_array[index] == 1
+      sum += (2 ** (7 - index))
+    end
+  end
+  return sum
+end
+