2nd

module2/exo1/toy_notebook_en.ipynb

 {
  "cells": [
-  {
-   "cell_type": "markdown",
-   "metadata": {
-    "hideCode": true,
-    "hidePrompt": true
-   },
-   "source": [
-    "<p align=\"center\">toy_notebook_en</p>"
-   ]
-  },
-  {
-   "cell_type": "markdown",
-   "metadata": {},
-   "source": [
-    "<p align=\"center\"> March 28, 2019 </p>"
-   ]
-  },
   {
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "## 1. On the computation of $\\pi$"
+    "# 1. On the computation of $\\pi$"
    ]
   },
   {
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "### 1.1. Asking the maths library"
+    "## 1.1. Asking the maths library"
    ]
   },
   {
@@ -60,7 +43,7 @@
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "### 1.2. Buffon's needle"
+    "## 1.2. Buffon's needle"
    ]
   },
   {
@@ -99,7 +82,7 @@
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "### 1.3. Using a surface fraction argument"
+    "## 1.3. Using a surface fraction argument"
    ]
   },
   {