diff --git a/problems/015_problem/015_problem.ipynb b/problems/015_problem/015_problem.ipynb
index 8783b73..c6a9e50 100644
--- a/problems/015_problem/015_problem.ipynb
+++ b/problems/015_problem/015_problem.ipynb
@@ -32,11 +32,13 @@
     " 1 1 0 0 <br>\n",
     "\n",
     "### A couple things that shake out of this,\n",
-    "1. The total length of a sequence of moves is the equal to Length + Width of the grid.\n",
+    "1. The total length of a sequence of moves is the equal to Length + Width of the grid.<br>\n",
+    "    1. So, for a 20x20, each sequence will be 40 moves in length.\n",
+    "    1. That could 2**40 possible combinations, most of which will not be valid.\n",
     "2. Each unique sequence of moves has a twin which is a mirror across the diagonal.\n",
     "3. Each valid sequence has an equal number of RIGHT and DOWN moves.\n",
     "\n",
-    "### I'm sure there is some combinatorial mathematics that describes how to do this analytically, but I'd rather practice programming a loop, than researching an elegant solution. \n",
+    "### I'm sure there is some combinatorial mathematics that describes how to do this analytically. That will require some research, so I'll save this problem for another day.\n",
     "\n",
     "---"
    ]
diff --git a/problems/016_problem/016_problem.ipynb b/problems/016_problem/016_problem.ipynb
new file mode 100644
index 0000000..fa2d2af
--- /dev/null
+++ b/problems/016_problem/016_problem.ipynb
@@ -0,0 +1,98 @@
+{
+ "cells": [
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "# Problem 16:\n",
+    " \n",
+    "### [Euler Project #16](https://projecteuler.net/problem=16)\n",
+    " \n",
+    "### 215 = 32768 and the sum of its digits is 3 + 2 + 7 + 6 + 8 = 26.\n",
+    "\n",
+    "### What is the sum of the digits of the number 21000?\n",
+    "\n",
+    "\n",
+    "---"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "### This seems pretty straightforward..."
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 1,
+   "metadata": {},
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "10715086071862673209484250490600018105614048117055336074437503883703510511249361224931983788156958581275946729175531468251871452856923140435984577574698574803934567774824230985421074605062371141877954182153046474983581941267398767559165543946077062914571196477686542167660429831652624386837205668069376\n"
+     ]
+    }
+   ],
+   "source": [
+    "big_integer=2**1000\n",
+    "print(big_integer)"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 11,
+   "metadata": {},
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "<class 'str'>\n",
+      "['1', '0', '7', '1', '5', '0', '8', '6', '0', '7', '1', '8', '6', '2', '6', '7', '3', '2', '0', '9', '4', '8', '4', '2', '5', '0', '4', '9', '0', '6', '0', '0', '0', '1', '8', '1', '0', '5', '6', '1', '4', '0', '4', '8', '1', '1', '7', '0', '5', '5', '3', '3', '6', '0', '7', '4', '4', '3', '7', '5', '0', '3', '8', '8', '3', '7', '0', '3', '5', '1', '0', '5', '1', '1', '2', '4', '9', '3', '6', '1', '2', '2', '4', '9', '3', '1', '9', '8', '3', '7', '8', '8', '1', '5', '6', '9', '5', '8', '5', '8', '1', '2', '7', '5', '9', '4', '6', '7', '2', '9', '1', '7', '5', '5', '3', '1', '4', '6', '8', '2', '5', '1', '8', '7', '1', '4', '5', '2', '8', '5', '6', '9', '2', '3', '1', '4', '0', '4', '3', '5', '9', '8', '4', '5', '7', '7', '5', '7', '4', '6', '9', '8', '5', '7', '4', '8', '0', '3', '9', '3', '4', '5', '6', '7', '7', '7', '4', '8', '2', '4', '2', '3', '0', '9', '8', '5', '4', '2', '1', '0', '7', '4', '6', '0', '5', '0', '6', '2', '3', '7', '1', '1', '4', '1', '8', '7', '7', '9', '5', '4', '1', '8', '2', '1', '5', '3', '0', '4', '6', '4', '7', '4', '9', '8', '3', '5', '8', '1', '9', '4', '1', '2', '6', '7', '3', '9', '8', '7', '6', '7', '5', '5', '9', '1', '6', '5', '5', '4', '3', '9', '4', '6', '0', '7', '7', '0', '6', '2', '9', '1', '4', '5', '7', '1', '1', '9', '6', '4', '7', '7', '6', '8', '6', '5', '4', '2', '1', '6', '7', '6', '6', '0', '4', '2', '9', '8', '3', '1', '6', '5', '2', '6', '2', '4', '3', '8', '6', '8', '3', '7', '2', '0', '5', '6', '6', '8', '0', '6', '9', '3', '7', '6']\n"
+     ]
+    }
+   ],
+   "source": [
+    "sum=0\n",
+    "sum+=big_integer%10\n",
+    "\n",
+    "str_big_integer=str(big_integer)\n",
+    "print(type(str_big_integer))\n",
+    "\n",
+    "list_big_integer=list(str_big_integer)\n",
+    "print(list_big_integer)"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": []
+  }
+ ],
+ "metadata": {
+  "kernelspec": {
+   "display_name": "Python 3",
+   "language": "python",
+   "name": "python3"
+  },
+  "language_info": {
+   "codemirror_mode": {
+    "name": "ipython",
+    "version": 3
+   },
+   "file_extension": ".py",
+   "mimetype": "text/x-python",
+   "name": "python",
+   "nbconvert_exporter": "python",
+   "pygments_lexer": "ipython3",
+   "version": "3.8.5"
+  }
+ },
+ "nbformat": 4,
+ "nbformat_minor": 4
+}