I hope you get every puzzle in this book wrong. I'm being honest. The more you answer incorrectly, the more fun you will have . . . Guardian puzzle master Alex Bellos knows better than anyone that the puzzles we find irresistible are the ones that deceive us. Those that seem blindingly, obviously simple - and yet we can't help but get wrong. These 70 confounding puzzles - which Alex has scoured from across psychology, mathematics, statistics, physics, geography, the science of perception and more - are guaranteed to catch you off guard. But why are you getting them wrong? And how can you get them right? In Think Twice, Alex delights in tripping us up and then returning us to our feet, explaining how these puzzles work, the biases holding us back - and how to train your brain to avoid being hoodwinked again. Think once and you will stumble. Think twice and you are in with a chance. Now that you've been warned, can you prove Alex wrong?