Monday puzzle: who will toss more heads?
Let's you and I play a game with coins. You have 100 dimes, and I have 99 pennies. At the same time, we will toss our coins in the air and let them fall on the floor. Then we meticulously count the outcomes of our tosses. You win if you show more ...

Monday puzzle: which lane is better?
You're on a two-lane highway and there are cars ahead of you in both lanes. You want to go straight ahead, but some of the cars in front of you might slow down to turn and delay you. You are in the left lane. In that lane, there are 3 cars, ...

Monday puzzle: the efficient drink order
Today's puzzle has a special extra. Because the problem is geometric in nature, I thought it would be fun to make a video of the puzzle on Youtube. Here is a link to the puzzle videos on Youtube. Efficient drink order problem - Youtube (it's just over at minute at 1 min 18 ...

The three coin puzzle
After a lucky day in the casino, a gambler is greeted by a beautiful woman in the hotel lobby. She congratulates the gambler on his success, and wonders if he would like to parlay those winnings into even more money. She offers the following bet:

Monday puzzle: fruit label stickers
This is a problem slightly modified from a 2002 Putnam competition question. I thought about this problem while eating a large grapefruit one morning. The puzzle Imagine a perfectly round grapefruit that is labeled with 5 fruit stickers. Prove that the grapefruit can be cut in two equal halves in which one of the ...

Monday puzzle: random music
Have you ever felt your iPod or music player's shuffle function was not working correctly? Today's problem is about how random events are not always perceived as random.

Puzzle: birthday line problem
Birthday problems always make for fun probability puzzlers. There's the famous birthday problem, and then there is one I wrote about before called birthday holidays. The following is a puzzle I have adapted from the website braingle.

Monday puzzle: flip until heads
Probability calculations often show counter-intuitive results. Here is a puzzle about the distribution of coin flips.

Monday puzzle: the moat crossing problem
This is a fun geometrical puzzle--refer to the picture below. Here is the problem:

Puzzle: the Riddler vs Batman and Robin
This is a puzzle adapted from Max Schireson's blog. It is based on the trope that villains tend to use elaborate execution schemes. Here is the problem:

Monday puzzle: the train fly problem
This is a classic math puzzle. Here is the problem:

Monday puzzle: digits in a book
I adapted this puzzle from a Wall Street Journal article about the new book Are you Smart Enough to Work at Google? I am quite excited about the book because it is written by William Poundstone, whose book I highly recommend. I have personally read How Would you Move Mount Fuji? ...

Monday puzzle: lady tasting tea problem
In a previous post, I discussed ways to design a better blind taste test. This puzzle is about a taste test with historic significance to statistics.

A determinant game
This is a fun combinatorial game theory problem I came across. This problem appeared in the 2008 Putnam exam, an annual North American college math competition:

Answer to puzzle leaving work quickly
This post explains the solution to the puzzle posted on Monday called leaving work quickly. Okay, so sorry to keep changing the format of the Monday puzzle and solution. It's a work in progress so let me explain my logic. (And please forgive a broken link or two as I'm figuring ...