3rd attempt

module2/exo1/toy_notebook_en.ipynb

 {
  "cells": [
-  {
-   "cell_type": "markdown",
-   "metadata": {},
-   "source": [
-    "<center>toy_notebook_en</center>\n",
-    "\n",
-    "<br>\n",
-    "<center>March 28, 2019</center>"
-   ]
-  },
   {
    "cell_type": "markdown",
    "metadata": {},
@@ -22,8 +12,6 @@
    "metadata": {},
    "source": [
     "## Asking the maths library\n",
-    "\n",
-    "\n",
     "My computer tells me that $\\pi$ is *approximately*"
    ]
   },
@@ -49,13 +37,7 @@
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "## Buffon’s needle"
-   ]
-  },
-  {
-   "cell_type": "markdown",
-   "metadata": {},
-   "source": [
+    "## Buffon’s needle\n",
     "Applying the method of [Buffons needle](https://en.wikipedia.org/wiki/Buffon%27s_needle_problem), we get the **approximation**"
    ]
   },
@@ -88,13 +70,7 @@
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "## Using a surface fraction argument"
-   ]
-  },
-  {
-   "cell_type": "markdown",
-   "metadata": {},
-   "source": [
+    "## Using a surface fraction argument\n",
     "A method that is easier to understand and does not make use of the sin function is based on the\n",
     "fact that if $X\\sim U(0,1)$ and $Y\\sim U(0,1)$, then $P[X^2+Y^2\\leq 1]=\\pi/4$ (see [\"Monte Carlo method\"\n",
     "on Wikipedia](https://en.wikipedia.org/wiki/Monte_Carlo_method)). The following code uses this approach:"