Presenter Carol Vorderman looks at our ability to calculate fractions and ratios - in particular our fascination with the 'golden ratio', expressed as 1.618. This ratio is found everywhere in nature and in the manmade world. George Ferguson, an architect, describes the use of geometry from ancient Greek times and the appearance of the ratio in nature. Carol goes on to demonstrate the use of the ratio in photography, which provides a formula for good composition. Our fascination with finding this ratio in our world is still something of a mystery.