diff --git a/stacks_queues/n_stacks/n_stacks_challenge.ipynb b/stacks_queues/n_stacks/n_stacks_challenge.ipynb
new file mode 100644
index 0000000..227514a
--- /dev/null
+++ b/stacks_queues/n_stacks/n_stacks_challenge.ipynb
@@ -0,0 +1,198 @@
+{
+ "cells": [
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "<small><i>This notebook was prepared by [Donne Martin](http://donnemartin.com). Source and license info is on [GitHub](https://github.com/donnemartin/coding-challenges).</i></small>"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "# Challenge Notebook"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Problem: Implement n stacks using a single array.\n",
+    "\n",
+    "* [Constraints](#Constraints)\n",
+    "* [Test Cases](#Test-Cases)\n",
+    "* [Algorithm](#Algorithm)\n",
+    "* [Code](#Code)\n",
+    "* [Unit Test](#Unit-Test)\n",
+    "* [Solution Notebook](#Solution-Notebook)"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Constraints\n",
+    "\n",
+    "*Problem statements are sometimes ambiguous.  Identifying constraints and stating assumptions can help to ensure you code the intended solution.*\n",
+    "\n",
+    "* Are the stacks and array a fixed size?\n",
+    "    * Yes"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Test Cases\n",
+    "\n",
+    "* Test the following on the three stacks:\n",
+    "    * Push to full stack -> Exception\n",
+    "    * Push to non-full stack\n",
+    "    * Pop on empty stack -> Exception\n",
+    "    * Pop on non-empty stack"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Algorithm\n",
+    "\n",
+    "Refer to the [Solution Notebook](http://nbviewer.ipython.org/github/donnemartin/coding-challenges/blob/master/stacks_queues/n_stacks/n_stacks_solution.ipynb).  If you are stuck and need a hint, the solution notebook's algorithm discussion might be a good place to start."
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Code"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {
+    "collapsed": true
+   },
+   "outputs": [],
+   "source": [
+    "class Stacks(object):\n",
+    "    \n",
+    "    def __init__(self, num_stacks, stack_size):\n",
+    "        # TODO: Implement me\n",
+    "        pass\n",
+    "\n",
+    "    def abs_index(self, stack_index):\n",
+    "        # TODO: Implement me\n",
+    "        pass\n",
+    "\n",
+    "    def push(self, stack_index, data):\n",
+    "        # TODO: Implement me\n",
+    "        pass\n",
+    "\n",
+    "    def pop(self, stack_index):\n",
+    "        # TODO: Implement me\n",
+    "        pass"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Unit Test\n",
+    "\n",
+    "\n",
+    "\n",
+    "**The following unit test is expected to fail until you solve the challenge.**"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [],
+   "source": [
+    "# %load test_n_stacks.py\n",
+    "from nose.tools import assert_equal\n",
+    "from nose.tools import raises\n",
+    "\n",
+    "\n",
+    "class TestStacks(object):\n",
+    "    \n",
+    "    @raises(Exception)\n",
+    "    def test_pop_on_empty(self, num_stacks, stack_size):\n",
+    "        print('Test: Pop on empty stack')\n",
+    "        stacks = Stacks(num_stacks, stack_size)\n",
+    "        stacks.pop(0)\n",
+    "\n",
+    "    @raises(Exception)\n",
+    "    def test_push_on_full(self, num_stacks, stack_size):\n",
+    "        print('Test: Push to full stack')\n",
+    "        stacks = Stacks(num_stacks, stack_size)\n",
+    "        for i in xrange(0, stack_size):\n",
+    "            stacks.push(2, i)\n",
+    "        stacks.push(2, stack_size)\n",
+    "\n",
+    "    def test_stacks(self, num_stacks, stack_size):\n",
+    "        print('Test: Push to non-full stack')\n",
+    "        stacks = Stacks(num_stacks, stack_size)\n",
+    "        stacks.push(0, 1)\n",
+    "        stacks.push(0, 2)\n",
+    "        stacks.push(1, 3)\n",
+    "        stacks.push(2, 4)\n",
+    "\n",
+    "        print('Test: Pop on non-empty stack')\n",
+    "        assert_equal(stacks.pop(0), 2)\n",
+    "        assert_equal(stacks.pop(0), 1)\n",
+    "        assert_equal(stacks.pop(1), 3)\n",
+    "        assert_equal(stacks.pop(2), 4)\n",
+    "\n",
+    "        print('Success: test_stacks\\n')\n",
+    "\n",
+    "def main():\n",
+    "    num_stacks = 3\n",
+    "    stack_size = 100    \n",
+    "    test = TestStacks()\n",
+    "    test.test_pop_on_empty(num_stacks, stack_size)\n",
+    "    test.test_push_on_full(num_stacks, stack_size)\n",
+    "    test.test_stacks(num_stacks, stack_size)\n",
+    "    \n",
+    "if __name__ == '__main__':\n",
+    "    main()"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Solution Notebook\n",
+    "\n",
+    "Review the [Solution Notebook](http://nbviewer.ipython.org/github/donnemartin/coding-challenges/blob/master/stacks_queues/n_stacks/n_stacks_solution.ipynb) for a discussion on algorithms and code solutions."
+   ]
+  }
+ ],
+ "metadata": {
+  "kernelspec": {
+   "display_name": "Python 2",
+   "language": "python",
+   "name": "python2"
+  },
+  "language_info": {
+   "codemirror_mode": {
+    "name": "ipython",
+    "version": 2
+   },
+   "file_extension": ".py",
+   "mimetype": "text/x-python",
+   "name": "python",
+   "nbconvert_exporter": "python",
+   "pygments_lexer": "ipython2",
+   "version": "2.7.10"
+  }
+ },
+ "nbformat": 4,
+ "nbformat_minor": 0
+}
diff --git a/stacks_queues/n_stacks/n_stacks_solution.ipynb b/stacks_queues/n_stacks/n_stacks_solution.ipynb
index b54e618..34ce773 100644
--- a/stacks_queues/n_stacks/n_stacks_solution.ipynb
+++ b/stacks_queues/n_stacks/n_stacks_solution.ipynb
@@ -4,7 +4,14 @@
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "<small><i>This notebook was prepared by [Donne Martin](http://donnemartin.com). Source and license info is on [GitHub](https://bit.ly/code-notes).</i></small>"
+    "<small><i>This notebook was prepared by [Donne Martin](http://donnemartin.com). Source and license info is on [GitHub](https://github.com/donnemartin/coding-challenges).</i></small>"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "# Solution Notebook"
    ]
   },
   {
@@ -26,7 +33,7 @@
    "source": [
     "## Constraints\n",
     "\n",
-    "*Problem statements are often intentionally ambiguous.  Identifying constraints and stating assumptions can help to ensure you code the intended solution.*\n",
+    "*Problem statements are sometimes ambiguous.  Identifying constraints and stating assumptions can help to ensure you code the intended solution.*\n",
     "\n",
     "* Are the stacks and array a fixed size?\n",
     "    * Yes"
@@ -39,9 +46,9 @@
     "## Test Cases\n",
     "\n",
     "* Test the following on the three stacks:\n",
-    "    * Push to full stack\n",
+    "    * Push to full stack -> Exception\n",
     "    * Push to non-full stack\n",
-    "    * Pop on empty stack\n",
+    "    * Pop on empty stack -> Exception\n",
     "    * Pop on non-empty stack"
    ]
   },
@@ -101,6 +108,7 @@
    "outputs": [],
    "source": [
     "class Stacks(object):\n",
+    "    \n",
     "    def __init__(self, num_stacks, stack_size):\n",
     "        self.num_stacks = num_stacks\n",
     "        self.stack_size = stack_size\n",
@@ -134,8 +142,7 @@
    "metadata": {},
    "source": [
     "## Unit Test\n",
-    "\n",
-    "*It is important to identify and run through general and edge cases from the [Test Cases](#Test-Cases) section by hand.  You generally will not be asked to write a unit test like what is shown below.*"
+    "\n"
    ]
   },
   {
@@ -149,20 +156,18 @@
      "name": "stdout",
      "output_type": "stream",
      "text": [
-      "Test: Pop on empty stack\n",
-      "Test: Push to full stack\n",
-      "Test: Push to non-full stack\n",
-      "Test: Pop on non-empty stack\n",
-      "Success: test_stacks\n",
-      "\n"
+      "Overwriting test_n_stacks.py\n"
      ]
     }
    ],
    "source": [
+    "%%writefile test_n_stacks.py\n",
     "from nose.tools import assert_equal\n",
     "from nose.tools import raises\n",
     "\n",
-    "class Test(object):\n",
+    "\n",
+    "class TestStacks(object):\n",
+    "    \n",
     "    @raises(Exception)\n",
     "    def test_pop_on_empty(self, num_stacks, stack_size):\n",
     "        print('Test: Pop on empty stack')\n",
@@ -193,13 +198,40 @@
     "\n",
     "        print('Success: test_stacks\\n')\n",
     "\n",
-    "if __name__ == '__main__':\n",
+    "def main():\n",
     "    num_stacks = 3\n",
     "    stack_size = 100    \n",
-    "    test = Test()\n",
+    "    test = TestStacks()\n",
     "    test.test_pop_on_empty(num_stacks, stack_size)\n",
     "    test.test_push_on_full(num_stacks, stack_size)\n",
-    "    test.test_stacks(num_stacks, stack_size)"
+    "    test.test_stacks(num_stacks, stack_size)\n",
+    "    \n",
+    "if __name__ == '__main__':\n",
+    "    main()"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 3,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "Test: Pop on empty stack\n",
+      "Test: Push to full stack\n",
+      "Test: Push to non-full stack\n",
+      "Test: Pop on non-empty stack\n",
+      "Success: test_stacks\n",
+      "\n"
+     ]
+    }
+   ],
+   "source": [
+    "run -i test_n_stacks.py"
    ]
   }
  ],
diff --git a/stacks_queues/n_stacks/test_n_stacks.py b/stacks_queues/n_stacks/test_n_stacks.py
new file mode 100644
index 0000000..bee6f48
--- /dev/null
+++ b/stacks_queues/n_stacks/test_n_stacks.py
@@ -0,0 +1,46 @@
+from nose.tools import assert_equal
+from nose.tools import raises
+
+
+class TestStacks(object):
+    
+    @raises(Exception)
+    def test_pop_on_empty(self, num_stacks, stack_size):
+        print('Test: Pop on empty stack')
+        stacks = Stacks(num_stacks, stack_size)
+        stacks.pop(0)
+
+    @raises(Exception)
+    def test_push_on_full(self, num_stacks, stack_size):
+        print('Test: Push to full stack')
+        stacks = Stacks(num_stacks, stack_size)
+        for i in xrange(0, stack_size):
+            stacks.push(2, i)
+        stacks.push(2, stack_size)
+
+    def test_stacks(self, num_stacks, stack_size):
+        print('Test: Push to non-full stack')
+        stacks = Stacks(num_stacks, stack_size)
+        stacks.push(0, 1)
+        stacks.push(0, 2)
+        stacks.push(1, 3)
+        stacks.push(2, 4)
+
+        print('Test: Pop on non-empty stack')
+        assert_equal(stacks.pop(0), 2)
+        assert_equal(stacks.pop(0), 1)
+        assert_equal(stacks.pop(1), 3)
+        assert_equal(stacks.pop(2), 4)
+
+        print('Success: test_stacks\n')
+
+def main():
+    num_stacks = 3
+    stack_size = 100    
+    test = TestStacks()
+    test.test_pop_on_empty(num_stacks, stack_size)
+    test.test_push_on_full(num_stacks, stack_size)
+    test.test_stacks(num_stacks, stack_size)
+    
+if __name__ == '__main__':
+    main()
\ No newline at end of file