Haha! That interview was quite short! It's obvious to me that Zhang was never in any of this for the fame or fortune he would receive by solving this problem, but instead he was in it for the pure joy of simply knowing the answer. I don't know if anybody else is like this, but when I get the right answer on a test question that I worked so hard to find the answer to... it's such a great feeling. That's the same way I think Zhang felt. He didn't want to become famous, he didn't want to be interviewed, he simply was in it for his great love of math.
Math is a beautiful thing indeed. It's all around us. I don't really think of it that way very often, but it is. In nature, we see patterns in all sorts of plants and perfect shapes and angles everywhere around us. Take the simple example of when you cut an apple down the middle, a perfect little star is formed. Simple, yet beautiful. Everything can be tied back to math!
