Can you find the next number in this sequence? – Alex Gendler
View full lesson: http://ed.ted.com/lessons/can-you-find-the-next-number-in-this-sequence-alex-gendler
1, 11, 21, 1211, 111221. These are the first five elements of a number sequence. Can you figure out what comes next? Alex Gendler reveals the answer and explains how beyond just being a neat puzzle, this type of sequence has practical applications as well.
Lesson by Alex Gendler, directed by Artrake Studio.



![[ID: lZpMXJ4TvaM] Youtube Automatic](https://myaiu.tv/wp-content/uploads/2026/06/id-lzpmxj4tvam-youtube-automatic-236x133.jpg)
![[ID: K80bqj6quJo] Youtube Automatic](https://myaiu.tv/wp-content/uploads/2026/06/id-k80bqj6qujo-youtube-automatic-236x133.jpg)
![[ID: pWDClKzlbAU] Youtube Automatic](https://myaiu.tv/wp-content/uploads/2026/06/id-pwdclkzlbau-youtube-automatic-236x133.jpg)
![[ID: lKUdNAGn9_E] Youtube Automatic](https://myaiu.tv/wp-content/uploads/2026/06/id-lkudnagn9e-youtube-automatic-236x133.jpg)
![Private: [ID: k7zdqnhY8b0] Youtube Automatic](https://myaiu.tv/wp-content/uploads/2026/06/private-id-k7zdqnhy8b0-youtube-a-236x133.jpg)
![Private: [ID: CY1CeFAYAok] Youtube Automatic](https://myaiu.tv/wp-content/uploads/2026/06/private-id-cy1cefayaok-youtube-a-236x133.jpg)