diff --git a/tutorials/sorting_csvs.ipynb b/tutorials/sorting_csvs.ipynb
index 04e99ab..237db52 100644
--- a/tutorials/sorting_csvs.ipynb
+++ b/tutorials/sorting_csvs.ipynb
@@ -1,7 +1,7 @@
 {
  "metadata": {
   "name": "",
-  "signature": "sha256:683cfd7e6b5fd1dca9cd2028b294ec8ae44a175b613eb3c037d365a28957a987"
+  "signature": "sha256:13c10e46fea51bcbbf203261897bb4d8ea2087e39925e077d452778f78d62b1e"
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  "nbformat": 3,
  "nbformat_minor": 0,
@@ -56,6 +56,7 @@
       "## Sections\n",
       "- [Reading in a CSV file](#reading)\n",
       "- [Printing the CSV file contents](#printing)\n",
+      "- [Converting numeric cells to floats](#floats)\n",
       "- [Sorting the CSV file](#sorting)\n",
       "- [Marking min/max values in particular columns](#marking)\n",
       "- [Writing out the modified table to as a new CSV file](#writing)\n",
@@ -140,7 +141,7 @@
      "language": "python",
      "metadata": {},
      "outputs": [],
-     "prompt_number": 1
+     "prompt_number": 4
     },
     {
      "cell_type": "code",
@@ -166,7 +167,7 @@
        ]
       }
      ],
-     "prompt_number": 3
+     "prompt_number": 5
     },
     {
      "cell_type": "markdown",
@@ -212,7 +213,7 @@
      "language": "python",
      "metadata": {},
      "outputs": [],
-     "prompt_number": 4
+     "prompt_number": 6
     },
     {
      "cell_type": "code",
@@ -245,7 +246,76 @@
        ]
       }
      ],
-     "prompt_number": 5
+     "prompt_number": 7
+    },
+    {
+     "cell_type": "markdown",
+     "metadata": {},
+     "source": [
+      "<a name='floats'></a>\n",
+      "<br>\n",
+      "<br>"
+     ]
+    },
+    {
+     "cell_type": "markdown",
+     "metadata": {},
+     "source": [
+      "## Converting numeric cells to floats"
+     ]
+    },
+    {
+     "cell_type": "markdown",
+     "metadata": {},
+     "source": [
+      "To avoid problems with the sorting approach that can occur when we have negative values in some cells, let us define a function that converts all numeric cells into float values."
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "def convert_cells_to_floats(csv_cont):\n",
+      "    \"\"\" \n",
+      "    Converts cells to floats if possible\n",
+      "    (modifies input CSV content list).\n",
+      "    \n",
+      "    \"\"\"\n",
+      "    for row in range(len(csv_cont)):\n",
+      "        for cell in range(len(csv_cont[row])):\n",
+      "            try:\n",
+      "                csv_cont[row][cell] = float(csv_cont[row][cell])\n",
+      "            except ValueError:\n",
+      "                pass "
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [],
+     "prompt_number": 8
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "print('first 3 rows:')\n",
+      "for row in range(3):\n",
+      "    print(csv_cont[row])"
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "first 3 rows:\n",
+        "['name', 'column1', 'column2', 'column3']\n",
+        "['abc', 1.1, 4.2, 1.2]\n",
+        "['def', 2.1, 1.4, 5.2]\n"
+       ]
+      }
+     ],
+     "prompt_number": 9
     },
     {
      "cell_type": "markdown",
@@ -304,7 +374,7 @@
      "language": "python",
      "metadata": {},
      "outputs": [],
-     "prompt_number": 5
+     "prompt_number": 10
     },
     {
      "cell_type": "markdown",
@@ -360,7 +430,7 @@
        ]
       }
      ],
-     "prompt_number": 6
+     "prompt_number": 11
     },
     {
      "cell_type": "markdown",
@@ -425,7 +495,7 @@
      "language": "python",
      "metadata": {},
      "outputs": [],
-     "prompt_number": 28
+     "prompt_number": 12
     },
     {
      "cell_type": "code",
@@ -447,7 +517,7 @@
      "language": "python",
      "metadata": {},
      "outputs": [],
-     "prompt_number": 29
+     "prompt_number": 13
     },
     {
      "cell_type": "code",
@@ -484,7 +554,7 @@
        ]
       }
      ],
-     "prompt_number": 32
+     "prompt_number": 14
     },
     {
      "cell_type": "markdown",
@@ -533,7 +603,7 @@
      "language": "python",
      "metadata": {},
      "outputs": [],
-     "prompt_number": 34
+     "prompt_number": 15
     },
     {
      "cell_type": "markdown",
@@ -573,7 +643,15 @@
        ]
       }
      ],
-     "prompt_number": 35
+     "prompt_number": 16
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [],
+     "language": "python",
+     "metadata": {},
+     "outputs": []
     }
    ],
    "metadata": {}