Why don't perpetual motion machines ever work? - Netta Schramm. Where do math symbols come from? - John David Walters. What's the fastest way to alphabetize your bookshelf? - Chand John. Why do airlines sell too many tickets? - Nina Klietsch. What's the difference between accuracy and precision? - Matt Anticole. How high can you count on your fingers? (Spoiler: much higher than 10) - James Tanton. The unexpected math behind Van Gogh's "Starry Night" - Natalya St. Clair. The Infinite Hotel Paradox - Jeff Dekofsky. Can you solve the bridge riddle? - Alex Gendler. Can you solve the prisoner hat riddle? - Alex Gendler. Can you solve "Einstein’s Riddle"? - Dan Van der Vieren. Can you solve the temple riddle? - Dennis E. Shasha. Can you solve the three gods riddle? - Alex Gendler. Can you solve the locker riddle? - Lisa Winer. Can you solve the passcode riddle? - Ganesh Pai. Can you solve the prisoner boxes riddle? - Yossi Elran. Can you solve the frog riddle? - Derek Abbott. Can you solve the counterfeit coin riddle? - Jennifer Lu. Can you solve the control room riddle? - Dennis Shasha. Can you solve the virus riddle? - Lisa Winer. Can you solve the airplane riddle? - Judd A. Schorr. Why do competitors open their stores next to one another? - Jac de Haan. Can you solve the river crossing riddle? - Lisa Winer. Can you solve the pirate riddle? - Alex Gendler. Exponential Growth: How Folding Paper Can Get You to the Moon. Can you solve the fish riddle? - Steve Wyborney. Can you solve the egg drop riddle? - Yossi Elran. Exploring other dimensions - Alex Rosenthal and George Zaidan. Why do honeybees love hexagons? - Zack Patterson and Andy Peterson. What is Zeno's Dichotomy Paradox? - Colm Kelleher. The mathematical secrets of Pascal’s triangle - Wajdi Mohamed Ratemi. Is math discovered or invented? - Jeff Dekofsky. Can you solve the dark coin riddle? - Lisa Winer. Group theory 101: How to play a Rubik’s Cube like a piano - Michael Staff. How to defeat a dragon with math - Garth Sundem. Check your intuition: The birthday problem - David Knuffke. One is one ... or is it?. The last banana: A thought experiment in probability - Leonardo Barichello. How many ways can you arrange a deck of cards? - Yannay Khaikin. Inside OKCupid: The math of online dating - Christian Rudder. What's an algorithm? - David J. Malan. Can you solve the seven planets riddle? - Edwin F. Meyer. A brief history of banned numbers - Alessandra King. The math behind Michael Jordan’s legendary hang time - Andy Peterson and Zack Patterson. The origin of countless conspiracy theories - PatrickJMT. How many ways are there to prove the Pythagorean theorem? - Betty Fei. The infinite life of pi - Reynaldo Lopes. How to spot a misleading graph - Lea Gaslowitz. A clever way to estimate enormous numbers - Michael Mitchell. Why do people get so anxious about math? - Orly Rubinsten. The case of the missing fractals - Alex Rosenthal and George Zaidan. What happens if you guess - Leigh Nataro. Making sense of irrational numbers - Ganesh Pai. How the Königsberg bridge problem changed mathematics - Dan Van der Vieren. Pizza physics (New York-style) - Colm Kelleher. The beauty of data visualization - David McCandless. Did Shakespeare write his plays? - Natalya St. Clair and Aaron Williams. The mathematics of sidewalk illusions - Fumiko Futamura. Why are manhole covers round? - Marc Chamberland. Can you find the next number in this sequence? - Alex Gendler. What is a vector? - David Huynh. A brief history of numerical systems - Alessandra King. The coin flip conundrum - Po-Shen Loh. The mighty mathematics of the lever - Andy Peterson and Zack Patterson. What in the world is topological quantum matter? - Fan Zhang. An introduction to mathematical theorems - Scott Kennedy. How algorithms shape our world - Kevin Slavin. How to visualize one part per million - Kim Preshoff + The TED-Ed Community. How does math guide our ships at sea? - George Christoph. How to organize, add and multiply matrices - Bill Shillito. The time value of money - German Nande. A trip through space to calculate distance - Heather Tunnell. Euclid's puzzling parallel postulate - Jeff Dekofsky. Math class needs a makeover - Dan Meyer. Gridiron physics: Scalars and vectors - Michelle Buchanan. Why can't you divide by zero? - TED-Ed. The beautiful math of coral - Margaret Wertheim. Fractals and the art of roughness - Benoit Mandelbrot. Symmetry, reality's riddle - Marcus du Sautoy. Building unimaginable shapes - Michael Hansmeyer. Can you solve the Mondrian squares riddle? - Gordon Hamilton. How exactly does binary code work? - José Américo N L F de Freitas. Can you solve the Leonardo da Vinci riddle? - Tanya Khovanova. The greatest mathematician that never lived - Pratik Aghor. The satisfying math of folding origami - Evan Zodl. The paradox at the heart of mathematics: Gödel's Incompleteness Theorem - Marcus du Sautoy. The method that can "prove" almost anything - James A. Smith.