A new product has a cycle – it is developed, it hits the market, becomes a 'must have', achieves an amazing sales growth and then loses its popularity and sales go into decline. This is what happened to Rubik's Cube following its invention in 1974 by Erno Rubik. However, the product life cycle of the Rubik's Cube has been revitalised several times over. The latest revival is through its promotion in the recent film WALL-E-, where the Rubik's Cube featured as the prized possession of a rubbish-collecting robot whose robot girlfriend EVE solves the puzzle in seconds. (The Times, 21 January, 2009).

This need to revitalise products occurs in many businesses. Kellogg's extended the product life cycle of its breakfast cereal bar Nutri-Grain to respond to market challenges and invigorate sales. Read the Times 100 case study on Kellogg's to find out how it extended the product life cycle of its Nutri-Grain bar.

The revival of Rubik's Cube has brought a new audience to the product not only as a toy or game but also as a scientific tool. This simple toy still poses analytical problems for mathematicians, who are currently trying to prove that any cube can be solved in 20 moves. This sort of analysis is important in navigation networks such as the internet, the national grid or even neural networks in the brain.