The spread of these black-market cubes challenges the London-based company with a marketing brain teaser.

WSJ: One Rubik's Cube, Many Knockoffs, Quintillions of Possibilities

Afterward, stop by the nature-themed gift shop, which sells gifts, books, toys and brain-teaser souvenirs.

BBC: Discover life in the Nevada desert

There's a big brain-teaser at the moment because life expectancy for men and women is going up.

BBC: NEWS | Programmes | Working Lunch | Pensions: Past, present and future