diff --git a/lib/binary_to_decimal.rb b/lib/binary_to_decimal.rb
index 439e8c6..8148de4 100644
--- a/lib/binary_to_decimal.rb
+++ b/lib/binary_to_decimal.rb
@@ -4,6 +4,15 @@
 # The least significant bit is at index 7.
 # 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
+  exponent = (binary_array.length) - 1
+  num = 0
+    
+  binary_array.each do |digit|
+    num += (digit * 2 ** exponent)
+    exponent -= 1
+  end
+  return num
 end
+