The first 200 people to sign up at https://brilliant.org/stevemould/ will get 20% off an annual subscription. Computers add numbers together using logic gates built out of transistors. But they don't have to be! They can be built out of greedy cup siphons instead! I used specially designed siphones to works as XOR and AND gates and chained them together so they add 4 digit binary numbers. Subscribe to Matt's channel so you don't miss his Dobble video: null Here's my greedy cup siphon video: https://www.youtube.com/watch?v=Cg8KQfaT9xY Image credits: Zoom in on transistor - NISENet Moniac - Matt Brown Moniac - Paul Downey Moniac - Tiia Monto Moniac - Marcin Wichary You can buy my books here: https://stevemould.com/books You can support me on Patreon here: https://www.patreon.com/stevemould just like these amazing people: Matthew Cocke Glenn Watson Joseph Rocca Joël van der Loo Doug Peterson Rashid Al M Paul Warelis Will Ackerly Heather Liu Alnitak Twitter: http://twitter.com/moulds Instagram: https://www.instagram.com/stevemouldscience/ Facebook: https://www.facebook.com/stevemouldscience/ Buy nerdy maths things: http://mathsgear.co.uk/