First, a few words from Justin:
Q: What was it like to have your story on Upworthy?
"When we were filming the first video, I jokingly told my students that I thought it could go viral. When we put it up and got a thousand views just by word of mouth, we were really pleased — that was about as viral as any of us expected. So after Upworthy picked it up and we got 25,000 views in 24 hours, my students were blown away. It helped get them jazzed to take on another puzzle!"
Q: Why do you do this exercise with your students?
"Every year I get the question in class, 'When are we gonna have to use this?' And my answer to that question is, 'You're not.' That's not the point. By doing math, we are carving neural pathways that otherwise wouldn't have been there. Grappling with problems like this makes us better problem solvers, and by extension, better human beings."
And finally, the counting puzzle, take 2: