"What If? maintains a delightfully free-wheeling tone throughout, especially when complicated calculations lead to whimsical results...Despite all the hard facts and gigantic numbers, it never feels like a textbook--and you don't have to be a rocket scientist to enjoy it. A." -- Entertainment Weekly

"Catchy and approachable...There's plenty of scientific rigor behind his elaborate explanations but he punctuates them with sly humor and winningly primitive cartoon diagrams...A cut above so many popular science and technology books." -- NPR.org

"Consistently fascinating and entertaining...Munroe leavens the hard science with whimsical touches...An illuminating handbook of methods of reasoning." -- Wall Street Journal

"It's fun to watch as Munroe tackles each question and examines every possible complication with nerdy and methodical aplomb, his distinctive scribblings providing clever running commentary of peanut-gallery jokes as his train of thought (sometimes) happily derails. The delightfully demented What If? is the most fun you can have with math and science, short of becoming your own evil genius...We feel the tug of Munroe's playful yet existentially-tinged worldview, and all that geek logic and number-crunching becomes unexpectedly poignant." -- Boston Globe

"Munroe has hit on a wonderful form of science and engineering communication that can do so much--extolling the value of analytical thinking, examining data, and doing back-of-the-envelope calculations--while entertaining readers at the same time... an incredibly fun book with quirky, hand-drawn pictures." -- American Scientist