A simple question from a six-year-old about hangman turned into another analysis obsession that made me play 15 million games of hangman recently. Back in 2007, I wrote a game of hangman for a human guesser on the train journey from Oxford to London. I spent the time on the London Underground thinking about optimal strategies for playing it, and wrote the version for the computer doing the guessing on the return journey. It successfully guessed my test words and I was satisfied, so I submitted both to the Wolfram Demonstrations Project. Now, three years later, my daughter is old enough to play, but the Demonstration annoys her, as it can always guess her words. She asked the obvious question that never occurred to me at the time: "What are the hardest words I can choose, so that I can beat it?"

I was reading about the IT problems of the recently arrested, alleged Russian spies, and I wondered if they could have managed secret communications better with Mathematica. One of the claims was that they were using digital steganography tools that kept crashing. I wanted to see how quickly I could implement digital image steganography in Mathematica using a method known as "least significant bit insertion". The idea of steganography is to hide messages within other information so that no one notices your communications. The word itself comes from a Latin-Greek combination meaning "covered writing", from earlier physical methods that apparently included tattooing a message on a messenger's head before letting him grow his hair back to hide it. In the case of digital steganography, it is all done in the math.