See more James Grime over on Singing Banana. null He is also on some channel called Numberphile. http://bit.ly/grimevideos We have some teacher notes and activity resources for this video on Think Maths. See if your students can find a better graphical proof for the case of 4k than we did! Spoiler: there is one. http://think-maths.co.uk/standupmaths-videos#two-squares CORRECTIONS - Nothing yet. Let me know if you spot anything! Thanks to my Patreon supports who do support these videos and make them possible. Here is a random subset: Daniel Brahneborg Jan Strohbeck Marcel de Jong Thomas Kristian Hodnemyr Linus Törnqvist Support my channel and I can make more maths videos: https://www.patreon.com/standupmaths Music by Howard Carter Filming and editing by Matt Parker Design by Simon Wright Some maths by James Grime. MATT PARKER: Stand-up Mathematician Website: http://standupmaths.com/ Maths book: http://wwwh.umble-pi.com/ Nerdy maths toys: http://mathsgear.co.uk/