The Dehn Invariant - Numberphile

It was #3 on Hilbert's list of the most important problems in mathematics - until his student solved it.
More links & stuff in full description below ↓↓↓

Featuring Daniel Litt, currently at the Institute for Advanced Study -

David Hilbert's problems:

Max Dehn's famed proof:

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Editing and animation by Pete McPartlan

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