diff --git a/numpy_questions.py b/numpy_questions.py
index 07a10c1..d59fb63 100644
--- a/numpy_questions.py
+++ b/numpy_questions.py
@@ -29,7 +29,7 @@ def max_index(X):
     Returns
     -------
     (i, j) : tuple(int)
-        The row and columnd index of the maximum.
+        The row and column index of the maximum.
 
     Raises
     ------
@@ -37,12 +37,15 @@ def max_index(X):
         If the input is not a numpy array or
         if the shape is not 2D.
     """
-    i = 0
-    j = 0
+    if not isinstance(X, np.ndarray):
+        raise ValueError("The input must be a numpy array.")
 
-    # TODO
+    if X.ndim != 2:
+        raise ValueError("The input array must be 2D.")
 
-    return i, j
+    max_idx = np.unravel_index(np.argmax(X, axis=None), X.shape)
+
+    return max_idx
 
 
 def wallis_product(n_terms):
@@ -64,4 +67,15 @@ def wallis_product(n_terms):
     """
     # XXX : The n_terms is an int that corresponds to the number of
     # terms in the product. For example 10000.
-    return 0.
+    if n_terms == 0:
+        wallis_product = 1
+    else:
+        wallis_product = 1
+        for n in range(n_terms):
+            term1 = (4*(n+1)**2)
+            term2 = term1-1
+            wallis_product = wallis_product*(term1/term2)
+
+    pi = 2*float(wallis_product)
+
+    return pi