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How many people are adherents to Islam?

Answer:
Around 1600 million Muslims; per Pew Forum study as of October 2009
There are somewhere between 1.25 and 1.84 billion Muslims (those who practice Islam) worldwide.


they list a few different sources, but they are all around the 1.3 billion mark.
First answer by Elosery. Last edit by Elosery. Contributor trust: 3057 [recommend contributor recommended]. Question popularity: 6 [recommend question].