The Moscow Puzzles – Ch. 1 (Pt. 1)

So way back a long time ago (I don’t even remember when) I bought a bunch of random math & physics problem books. It must have been when I wanted to be a physics god so late high school or early college.


Anyways. One of the books I got is called “The Moscow Puzzles” by Boris Kordemsky. Supposedly (from the book’s introduction) this was the most popular mathematics puzzle book ever published in the Soviet Union.

I went through a few of the problems today, and I think I’ll make this a daily, or at least almost daily thing. After doing a couple I figured maybe it’d be a fun thing to share here. So each post will just have whatever problems I went through for the day with the solutions.

Chapter 1 – “Amusing Problems”

The intro for chapter 1 says this:

To see how good your brain is, let’s first put it to work on problems that require only perseverance, patience, sharpness of mind, and the ability to add, subtract, multiply, and divide whole numbers.

1. Observant Children

A schoolboy and a schoolgirl have just completed some meteorological measurements. They are resting on a knoll. A freight train is passing, its locomotive fiercely fuming and huffing as it pulls the train up a slight incline. Along the railroad bed the wind is wafting evenly, without gusts.

“What wind speed did our measurements show?” the boy asked.

“Twenty miles per hour.”

“That is enough to tell me the train’s speed.”

“Well now.” The girl was dubious.

“All you have to do is watch the movement of the train a bit more closely.”

The girl thought awhile an also figured it out.

What was the train’s speed?

See answer The speed is 20 mph. The only way you’d be able to tell the speed of the train is by observing the smoke coming out of it. If the smoke appears to be going straight up, you’d know it is going the same speed as the wind.

3. Moving Checkers

Place 6 checkers on a table in a row, alternating them black, white, black, white, black, white. (Here, X = black, O = white)

[ ] [ ] [ ] [ ] [X] [O] [X] [O] [X] [O]

Leave a vacant place large enough for 4 checkers on the left.

Move the checkers so that all the white ones will end on the left, followed by all the black ones. The checkers must be moved in pairs, taking 2 adjacent checkers at a time, without disturbing their order, and sliding them to a vacant place. To solve this problem, only three such moves are necessary.

See answer
Start:  [ ] [ ] [ ] [ ] [X] [O] [X] [O] [X] [O]
Move 1: [ ] [ ] [O] [X] [X] [ ] [ ] [O] [X] [O]
Move 2: [ ] [ ] [O] [X] [X] [X] [O] [O] [ ] [ ]
Move 3: [O] [O] [O] [X] [X] [X] [ ] [ ] [ ] [ ]

4. Three Moves

Place three piles of matches on a table, one with 11 matches, the second with 7, and the third with 6. You are to move matches so that each pile holds 8 matches. You may add to any pile only as many matches as it already contains, and all the matches must come from one other pile. For example, if a pile holds 6 matches, you may add 6 to it, no more or less. You have three moves.

See answer
Start:  [11 matches] [7 matches]  [6 matches]
Move 1: [4 matches] [14 matches] [6 matches] -> move 7 from the 11 pile
Move 2: [4 matches] [8 matches] [12 matches] -> move 6 from the 14 pile
Move 3: [8 matches] [8 matches] [8 matches] -> move 4 from the 12 pile

My Skribbl Chrome Extension!

I just made a post about how I haven’t been getting anything done lately due to some mental health difficulties. Well, I figured that in the meantime I could show you guys my skribbl.io Chrome extension!

(Link to the extension is here if you are interested)

If you don’t know what skribbl is, basically everyone takes turns drawing pictures of random things that the game makes you choose from. Everyone who isn’t drawing has to try and guess what it is you’re drawing as fast as possible. The faster they guess, the more points they get. The more people that guess correctly, the more points the drawer gets.

This is how the game looks:

And I really sucked at this game. I’m not good with words and it turns out my imagination is lacking quite a bit when trying to see what other people see.

Looking at the top you can see there are four underscores “____” which tells you the word has four letters. As the timer ticks down, it will randomly fill in some of the letters as hints.

Despite all the hints and time I was still really bad at the game, so I decided I would try to make an extension to help myself out. I’d never used JavaScript for anything but dang it I would do anything to stop being in last every round.

So after a long day of trying to figure out what the heck JavaScript is, I had it! Here’s what it does:

#1, as you can see below, it shows you how many letters there are. In this case, a 4 letter word followed by a three letter word. It also shows you the letter counts on the bottom right where you type your guess.

Once the letters start coming in, it will also show them on the bottom right where you’re typing.

Lastly, it will highlight your box to let you know if you’re on the right or wrong track. Orange is neutral – it doesn’t know whether you’re doing anything wrong yet.

If it highlights red, it means you’ve done something wrong. For example, if the word has 7 letters but you’ve typed in 8, it will be red. Or, as in the case of the picture below, the letters I typed don’t match the letters the game gave me. I saw two e’s and typed “sleep”, but I had a p where the game knows I need to have an e, so it highlighted red.

So in my opinion it’s a super useful little thing to have on your side when playing. Again, I really just made it for myself so I could have an easier time competing against friends (everyone agreed that if I was going to bother to go to this much effort to play better, it wouldn’t count as cheating, so don’t worry about that!)

The coolest most feel-good part about all of this, though, is how many people have actually ended up using it!

I was amazed when it hit 50 active users, and then 100, and was beyond hyped when it hit 1000! Over the past year it has steadily continued to grow and now has almost 3,600 weekly active users.

Looking by region, I can see that over its history, people from 133 different countries have used my Skribbl Helper extension!

To a lot of people this would be a little baby project with little baby numbers. But I really can’t express how cool it feels to me that thousands of people from over 100 countries have used the little tool that I made to suck a little bit less at everyone’s favorite early-quarantine game.

Just figured I’d post something positive and also tick off the box of posting about something that I’ve made.

If you play Skribbl, try it out!

Pardon the Interruption

Hey all. I planned on being much more active on here when I first put this version of my site up, but it didn’t happen that way.

I have OCD and have had it since I was pretty young. The vast majority of the time my symptoms aren’t bad enough to interfere much with my day to day life. Lately they have been.

I haven’t been super functional for the past month or so, but I’ve since gotten a new care team and am back on the path to feeling normal.

I’d hoped to put out a book rec on here at least once or twice a month but it’s already been over a month since the last one and I’m 20% through the book. So it’ll be a while.

I can’t wait to start sharing the cool things I read and do once I’m back to doing more stuff again!

Until then

Book Rec: One Day in the Life of Ivan Denisovich

Finished: 2021-03-28

Amazon affiliate link (kindle version, best translation)

YouTube link to the movie (pretty good, IMDB here)

This book was simply amazing. You’re sitting there reading an entire book about one day in a prisoner’s life. A day that Solzhenitsyn assures us is really no different than any of the others in Ivan’s 10 year sentence. Yet, it is one of the most gripping stories I’ve read.

I was motivated to read this mainly because of how politicized everything is. People calling each other communists and fascists left and right. It just made me want to read something about one of them. I decided to read something relating to either communism or fascism, and went with communism because we learn plenty about the Nazis in school.

If you’re interested in the book, whether or not you use my affiliate link, get the Willets translation. This is the translation linked (at least the Kindle version is). I’ll let an Amazon reviewer with much more knowledge than me speak to why this is the best translation:

The work was a huge critical success in the Soviet Union due to its nuanced integration of peasant vernacular and prison slang into its narrative structures. The older translations of this novel, which were originally released in the 60s, use stiff literary language and simply do not capture the idiom of the original . In addition, I believe Willetts’ translation is still the only authorized one by the author, which includes sections that were not redacted or censored by the government during the original publication.

mkw

My Reading list

EDIT: 2021-12-01

I give up on maintaining a reading list. I’m usually reading several at once and take forever to finish them, and also realized I hate taking the time to review them, and no one really reads these anyways.

This first post will just be a log of the books I’m reading. I never read much before a year or two ago. Recently I’ve started reading a lot more. I might end up reorganizing this into separate posts for books I really like, but mostly (for now) this will just be a log.

One Day in the Life of Ivan Denisovich – Aleksandr Solzhenitsyn (Finished 2020-03-28)

The Selfish Gene – Richard Dawkins (In progress, post coming soon)