diff --git a/calculator.py b/calculator.py
index a46affd..ba8641f 100644
--- a/calculator.py
+++ b/calculator.py
@@ -40,45 +40,91 @@
 
 
 """
-
-
+def instructions():
+  """ Returns and instructional page at root """
+  page = """
+  <h1>How to use this page</h1>
+  <h2> Instructions </h2>
+  For the following cases, replace the numbers 3 & 4 with the numbers you wish to use in the search box.<br>
+  The first number is acted on by the second.  e.g. divide/3/4 would be 3 divided by 4.
+    <ol>
+      <li> For addition use: <a href="add/3/4">add/3/4</a></li>
+      <li> For subtraction use: <a href="subtract/3/4">subtract/3/4</a></li>
+      <li> For multiplication use: <a href="multiply/3/4">multiply/3/4</a></li>
+      <li> For division use: <a href="divide/3/4">divide/3/4</a></li>
+    </ol>   
+  """
+  return page
+
+
+  # return str([])
 def add(*args):
     """ Returns a STRING with the sum of the arguments """
 
     # TODO: Fill sum with the correct value, based on the
     # args provided.
-    sum = "0"
+    sum_val = str(sum(map(int, args)))
+    return sum_val
+
+def subtract(*args):
+  """ Returns a STRING with the difference of the arguments """
+  return str(int(args[0]) - int(args[1]))
+  
 
-    return sum
+def multiply(*args):
+  """ Returns a STRING with the product of the arguments """
+  return str(int(args[0])*int(args[1]))
 
-# TODO: Add functions for handling more arithmetic operations.
+def divide(*args):
+  """ Returns a STRING with the quotient of the arguments """
+  return str(int(args[0]) / int(args[1]))
 
 def resolve_path(path):
     """
     Should return two values: a callable and an iterable of
     arguments.
     """
+    funcs = {
+      '': instructions,
+      'add': add,
+      'subtract': subtract,
+      'multiply': multiply,
+      'divide': divide
+    }
+
+    path = path.strip('/').split('/')
+
+    func_name = path[0]
+    args = path[1:]
 
-    # TODO: Provide correct values for func and args. The
-    # examples provide the correct *syntax*, but you should
-    # determine the actual values of func and args using the
-    # path.
-    func = add
-    args = ['25', '32']
+    try:
+      func = funcs[func_name]
+    except KeyError:
+      raise NameError
 
     return func, args
 
 def application(environ, start_response):
-    # TODO: Your application code from the book database
-    # work here as well! Remember that your application must
-    # invoke start_response(status, headers) and also return
-    # the body of the response in BYTE encoding.
-    #
-    # TODO (bonus): Add error handling for a user attempting
-    # to divide by zero.
-    pass
+    headers = [("Content-type", "text/html")]
+    try:
+      path = environ.get("PATH_INFO", None)
+      if path is None:
+        raise NameError
+      func, args = resolve_path(path)
+      body = func(*args)
+      status = "200 OK"
+    except NameError:
+      status = "404 Not Found"
+      body = "<h1>Not Found</h1>"
+    except ZeroDivisionError:
+      status = "400 Bad Request"
+      body = "<h1>Divide by zero not allowed</h1>"
+    finally:
+      headers.append(('Content-length', str(len(body))))
+      start_response(status, headers)
+      return [body.encode('utf8')]
 
 if __name__ == '__main__':
-    # TODO: Insert the same boilerplate wsgiref simple
-    # server creation that you used in the book database.
-    pass
+    from wsgiref.simple_server import make_server
+    srv = make_server('localhost', 8080, application)
+    srv.serve_forever()