# Riddler Express – 1/11/2019

This week’s Riddler Express is about finding small factors of large numbers. The goal is to find the missing digit of the number below with factors all less than 100.

530,131,801,762,787,739,802,889,792,754,109,70_,139,358,547,710,066,257,652,050,346, …294,484,433,323,974,747,960,297,803,292,989,236,183,040,000,000,000

It turns out that Python is well equipped to handle a problem like this. The solution follows.

# Riddler Express – 1/4/2019

This weeks Riddler Express is deceptively difficult. I say that I fell for the simple solution and did not catch it until it was too late.

The problem starts with an encyclopedia with 20 volumes. Each volume is 2 cm thick, and has a cover that is 2 mm thick. A bookworm wiggles to page one of volume one. The worm then eats through each volume to the last page of volume 20. The problem is to find how far the worm travels.

The solution is below.

# Riddler Express – 12/21/2018

This week’s Riddler Express is about Santa hitching up the reindeer. He does not remember the order of the reindeer, with the exception of that showoff Rudolph. The reindeer can tell Santa if they are in the correct position, but cannot tell any more information.

Santa’s solution is to try the reindeer one at a time at the front of the sleigh until he gets the correct one. Then, he moves on to the next position. It takes Santa one minute to hitch up one reindeer. The question is to find out how long to expect this process to take. The answer is below.

# Riddler Classic – 12/21/2018

This week’s Riddler Classic is about using probability to estimate the length of a playlist.

Santa’s elves are working in the workshop and listening to 100 songs each shift. About half of the time, there is at least one song that is repeated. The problem is to use the information above to find the length of Santa’s playlist.

The solution is below.

# Riddler Classic – 12/14/2018

This week, the Riddler asks if you can win at tic-tac-toe blindfolded. It turns out that with some planning, you can either win or force a draw.

To start, the squares in the board are numbered as follows.

$\begin{tabular}{c|c|c} 1 & 2 & 3 \\ \hline 4 & 5 & 6 \\ \hline 7 & 8 & 9 \end{tabular}$

You get to go first, but you do not know your opponents moves. If you call a square that is already taken, you have to choose another square.

The algorithm for choosing your moves is in the flow chart below.

# Writing Tools

It is unusual for me to be (mostly) caught up on grading during finals week. I have been able to chip away at my book project during the evenings. A workflow has developed over the past week. One of the main decisions I had to make was what software to use for my writing. Here is what I am using at the moment.

# Outline and Notes – OneNote

I am currently working on the outline of the book. At the same time, I am researching teaching programming. The tool I use to keep both the outline and research is OneNote from Microsoft.

OneNote is Microsoft’s best software, after Outlook. The fact that it is a free app for Windows, Android, and the web means I can sync my notes across multiple devices. The formatting is impressive in OneNote. I can tag todo items as well, meaning I can use OneNote to keep track of my writing progress.

# Main Writing Computer – Linux Mint

My personal computer is running Linux Mint. I am very comfortable working on Linux. It lets me use, or reuse, older computers efficiently.

GNU/Linux is an open source operating system. I have used it for years, going back to Red Hat 5.1. When I was in graduate school, I built three separate Beowulf clusters for parallel processing. My Ph.D. dissertation was written on Linux.

I have set up a computer for writing and other work that is away from the common areas in my house. This computer was rescued from an electronics recycling program at my college. For fun, I take the useable computers home and upgrade them if possible. I wipe the hard drives and install Linux.

Of the many Linux distributions I have tried, Linux Mint hits the sweet spot between ease of use and stability. I have never had a problem with it crashing or failing to boot. Since Mint is based on the popular Ubuntu distribution, there are many packages available for download. I have found Ubuntu to be usable, but unstable.

# Writing Software – LaTeX

Since my book will feature many equations, it will be written using the typesetting package $\LaTeX$. Like Linux, I have been using $\LaTeX$ in my work for decades. $\LaTeX$ is supported by the publishers to whom I intend to submit my writing. It is not easy to work with $\LaTeX$ at first. Once you get the hang of it, $\LaTeX$ is a powerful tool for authors.

$\LaTeX$ is a standard in the mathematics community for typing mathematics. My Ph.D. dissertation was written in $\LaTeX$. I also used it in my teaching in graduate school. One of the reasons I chose WordPress for hosting my blog is that $\LaTeX$ support is built-in. I have used it three times in this paragraph alone.

When researching submission requirements for various publishers, I found that almost all want manuscripts submitted in PDF format. That means I could use $\LaTeX$ or Microsoft Word. When I discovered that Wiley provide a book template for $\LaTeX$, that was the deciding factor.

A document in $\LaTeX$ starts as a plain text file and is then compiled into a PDF document or some other format. This may seem like a lot of work when compared to Microsoft Word. However, if you need to change the formatting of one aspect of the document, like the headings, then recompiling the document ensures that the changes are applied correctly.

The other advantage of $\LaTeX$ is that is keeps track of the table of contents, bibliographic references, and index. The steps in tracking these references can be automated using a Makefile in the same way that compiling a program is automated. This is not for all authors, but it works just fine for me.

The project is moving forward. The software seems to be helping and not getting in the way. I will report back on how the tools are working as I get further down the road.

# Learning Project: Writing a Book

It is finals week at my college. The busyness of the semester is mostly over. The days are shorter. Now is the perfect time for reflection and looking forward to the new year. After some thought I have decided to start a new project with the goal of finishing by June. The task is writing a book.

During my most recent bout of introspection, I have realized that I am drifting away from my original purpose for starting this blog. The intention was to do projects to learn new skills and present the results, with the goal was to inspire others to learn and share in kind. After rereading the original few posts, I realized I was writing about myself more than I should.

Starting a new project is designed to make my writing here more useful for others. Since I was planning on writing a book related to my teaching, it makes sense to write about the process of writing here. Writing a book is a massive learning project, as I was never much of a writer. I have often described the relationship with my English teachers as “mutually traumatic”.

The motivation for writing a book came from my recent work on problems from “The Riddler“. In the process of working on some of the solutions, I realized that my students could benefit from some of the techniques I used. Also, watching my children going through high school math, I see that my students learned in a more technologically advanced setting than I did. From my initial searches, I could not find a book on the subject, so I decided to write it myself.

Over the next few months, I plan on sharing my progress on the book. I will not be sharing details on the book contents. I will be explaining my process as well as the lessons I learn and resources I use.