By Wesley StephensonBBC News

As Pope Benedict XVI prepares to step down next week, speculation is intensifying as to who will lead the reported 1.2 billion Catholics worldwide. But how did the Vatican arrive at that figure?

The figure of 1.2 billion, in theory, represents the number of people who have been baptised into the Catholic faith.

This might seem like an easy figure to calculate. Many people assume that when someone is baptised this is recorded and passed on to the Vatican.

But religious organisations vary in how much importance they attach to keeping good statistics, according to David Voas, professor of population studies at the University of… Read the rest @ http://www.bbc.co.uk/news/magazine-21545819

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