I applied when I was in college. They asked me some typical behavioral interview questions, then a few math/physics brainteasers, since I was a physics major. These included: 1.) If you had an infinite plane of quarters placed as close together as possible, what's the percentage of the area that empty space occupies? (Break down into a triangle of quarters) 2.) What's the speed of a point at the top of a wheel relative to the bottom? 3.) How many points and vertices are there in a 4-dimensional hypercube?