Here's a simple, but clever, project from New York designer Aakash Nihalani. Tape on walls makes mathematical equations out of everyday objects: one window plus one window equals two windows, for example. It's the kind of intervention that makes you take a second look at the buildings you pass every day. Below, a few more images from Nihalani's Sum Times project.
 Images courtesy of Aakash Nihalani.
 















 Otis knew before they did.