How many people in speak Mandarin?
Mandarin Chinese while not the most widely spoken language in the world is the language spoken by the most people around the world.
It's hard to say how many people speak Mandarin world wide. Due to the countries national language or required learning languages include Mandarin Chinese the following can be assumed:
Population of China: 1.4 billion
Population of Taiwan: 23 million
Population of Singapore: 4.58 million
Total of three countries: 1.427 billion
(Figures are approximations as of June 2008)
This doesn't include the Chinese that have immigrated to other countries. Nor does it include countries where their may be other Mandarin speakers such as Malaysia. The ultimate figure would possibly be much higher.