What is a better fit: a square peg in a round hole, or a round peg in a square hole?Your music player seems to be playing the same songs over again. Is there something wrong with the shuffle feature, or might the songs be playing randomly?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 heads than I do. What's the probability that you will win?The YouTube channel and blog Mind Your Decisions has blog posts and original videos about math that have been viewed millions of times. The problems in this book are based on some of the best puzzles in counting, geometry, and probability and game theory.