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