But in fact, the main reason for the two indices rising at different rates is because they use different arithmetical methods for calculating average prices.
Russell and Whitehead suggested no new numbers or arithmetical rules, but they did try to show how the simplest numbers integers could be built using the principles of logic.
Nathalie Tzourio-Mazoyer at the University of Caen, in France, and her colleagues, measured the brain activity of a maths prodigy as he performed some feats of arithmetical acrobatics.