diff --git a/module3/exo3/exercice.ipynb b/module3/exo3/exercice.ipynb
index 161d47f20d1a280cbcb235b03522a8752f419286..2d1cc778f7c243851b32451950701f590f05c7b1 100644
--- a/module3/exo3/exercice.ipynb
+++ b/module3/exo3/exercice.ipynb
@@ -9,8 +9,8 @@
     "Data obtained [here](https://scrippsco2.ucsd.edu/assets/data/atmospheric/stations/in_situ_co2/monthly/monthly_in_situ_co2_mlo.csv)\n",
     "\n",
     "\n",
-    "## 1. Import Data\n",
-    "Check if the DATA has already been downloaded to avoid downloading the data at every execution . If not, it download it and import it."
+    "## Import Data\n",
+    "Check if the DATA has already been downloaded to avoid downloading at every execution. If not, it download it and import it."
    ]
   },
   {
@@ -1143,7 +1143,7 @@
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "## 2. Data formatting\n",
+    "##  Data formatting\n",
     "\n",
     "The raw data is not ready for analysis. \n",
     "The two first lines are used to comment the rows:\n",
@@ -1156,7 +1156,9 @@
   {
    "cell_type": "code",
    "execution_count": 3,
-   "metadata": {},
+   "metadata": {
+    "scrolled": true
+   },
    "outputs": [
     {
      "data": {
@@ -2399,7 +2401,7 @@
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "## 3. Plotting the data\n",
+    "## Plotting the data\n",
     "\n",
     "We are now able to plot the CO$_2$ concentration for every years."
    ]
@@ -2485,7 +2487,7 @@
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "## 4. Analysis\n",
+    "## Analysis\n",
     "\n",
     "As shown in the previous plot, we can see a *high* frequency oscillation coupled to a slow increase.\n",
     "\n",
@@ -2570,7 +2572,7 @@
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "## 4. Result of the extrapolation\n",
+    "## Result of the extrapolation\n",
     "\n",
     "Now that we are conviced by the $x^2$ fit, we can extrapolate the data for the year 2025."
    ]
diff --git a/module3/exo3/exercice.pdf b/module3/exo3/exercice.pdf
new file mode 100644
index 0000000000000000000000000000000000000000..7255c8e7de10ebbdfebf1399ad1a4035baa0d7c6
Binary files /dev/null and b/module3/exo3/exercice.pdf differ