The <a href="https://en.wikipedia.org/wiki/British_flag_theorem" class="extiw" title="w:British flag theorem">British flag theorem</a>: the total area of the red squares equals the total area of the blue squares.
<a href="//commons.wikimedia.org/wiki/User:David_Eppstein" class="mw-redirect" title="User:David Eppstein">David Eppstein</a>
<span class="int-own-work" lang="en">Own work</span>