diff --git a/05_numbers/04_summary.ipynb b/05_numbers/04_summary.ipynb
new file mode 100644
index 0000000..45c7c29
--- /dev/null
+++ b/05_numbers/04_summary.ipynb
@@ -0,0 +1,85 @@
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+   "source": [
+    "# Chapter 5: Numbers & Bits (TL;DR)"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {
+    "slideshow": {
+     "slide_type": "skip"
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+   "source": [
+    "There exist three numeric types in core Python:\n",
+    "- `int`: a near-perfect model for whole numbers (i.e., $\\mathbb{Z}$); inherently precise\n",
+    "- `float`: the \"gold\" standard to approximate real numbers (i.e., $\\mathbb{R}$); inherently imprecise\n",
+    "- `complex`: layer on top of the `float` type to approximate complex numbers (i.e., $\\mathbb{C}$); inherently imprecise\n",
+    "\n",
+    "Furthermore, the [standard library <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_py.png\">](https://docs.python.org/3/library/index.html) provides two more types that can be used as substitutes for the `float` type:\n",
+    "- `Decimal`: similar to `float` but allows customizing the precision; still inherently imprecise\n",
+    "- `Fraction`: a near-perfect model for rational numbers (i.e., $\\mathbb{Q}$); built on top of the `int` type and therefore inherently precise\n",
+    "\n",
+    "The *important* takeaways for the data science practitioner are:\n",
+    "\n",
+    "1. **Do not mix** precise and imprecise data types, and\n",
+    "2. actively expect `nan` results when working with `float` numbers as there are no **loud failures**.\n",
+    "\n",
+    "The **numerical tower** is Python's way of implementing various **abstract** ideas of what numbers are in mathematics."
+   ]
+  }
+ ],
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+   "display_name": "Python 3",
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+    "left": "10px",
+    "top": "150px",
+    "width": "384px"
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+ "nbformat_minor": 4
+}
diff --git a/README.md b/README.md
index 4d3340b..098db41 100644
--- a/README.md
+++ b/README.md
@@ -136,6 +136,7 @@ Alternatively, the content can be viewed in a web browser
       [<img height="12" style="display: inline-block" src="static/link/to_mb.png">](https://mybinder.org/v2/gh/webartifex/intro-to-python/develop?urlpath=lab/tree/05_numbers/03_appendix.ipynb)
       (`Decimal` Type;
        `Fraction` Type)
+    - [summary <img height="12" style="display: inline-block" src="static/link/to_nb.png">](https://nbviewer.jupyter.org/github/webartifex/intro-to-python/blob/develop/05_numbers/04_summary.ipynb)
 
 
 #### Videos