For those who crave algebra's number circus, the Binary Watch ($95) displays time in binary format. It doesn't actually display zeroes and ones, instead turning specific LEDs on or off. The LEDs are organized in two rows: the top one indicates hours, with four lights valuing 8-4-2-1, and the bottom row shows minutes, with six lights valuing 32-16-8-4-2-1. To tell the time, you add up each row's lit LEDs, assuming your math skills are up to the challenge. If not, you can just admire the cool high-tech design, like any perplexed onlookers. Made of stainless steel, the watch is water resistant to 90 feet. If you find conventional watch faces "too easy," the Binary Watch is a good way to get your mathematical juices flowing.