That calculation would take the number of estimated cases of norovirus across Scotland in 2012 to more than one million.

BBC: 'One in five' struck by norovirus in Scotland, say experts

Natural gas emits half as much carbon dioxide as coal when used to make electricity, though the calculation fails to take into account the release of methane from natural-gas wells and pipelines, which also contributes to climate change.

WSJ: Rise in U.S. Gas Production Fuels Unexpected Plunge in Emissions

Although the theory that describes the interaction of quarks and gluons is on a firm conceptual footing, it is so complicated in practice that it can take years to make a single calculation of something like the shape of a proton even using the most powerful supercomputers.

ECONOMIST: Protons: Holey grail | The

The calculation for patients: Skip the test and take your chances, or cut out the cancer early and risk post-surgery downsides like incontinence, impotence and a lot of discomfort.

FORBES: Magazine Article

Changing the figure to take account of the cycle would make more sense, but it would introduce a complex and disputable new calculation, with countries arguing endlessly over precisely where they were in the cycle.

ECONOMIST: Europe's fiscal follies