Play Countdown number puzzles against the clock, or let the app find solutions to puzzles you set up. Countdown number puzzles require you to work out a sequence of calculations with six numbers whose final result is as close to a random target number as possible. You can play solo, practice, or play against the computer with three different skill levels. The app shows you solutions to all puzzles, and keeps statistics and leaderboards about how well you've been solving the puzzles.