How many languages are there? and other questions answered

For the answer to this question and questions like it, turn to:

Ethnologue
An encyclopedic reference work cataloging all of the world’s 6,909 known living languages
http://www.ethnologue.com/

Here are some facts from this website

• 58,100,000 in United Kingdom speak English
• 215,000,000 in United States (2000 census)
• 328,008,138 people in the world speak English

Note: It is claimed that more people speak English in China than in America.  I haven't found any conclusive evidence of this yet.  If you see some, please comment below)

Which language has the most speakers in the world?
For an easy to understand answer to this question, see Wikipedia
http://en.wikipedia.org/wiki/List_of_languages_by_number_of_native_speakers

According to Wiki, English is number 3.  Behind Mandarin and Spanish.
Please note though, this only counts native English speakers.
If you take those who speak English as a second language into consideration, then it gets hairy.  Because it is difficult to classify.  Do you count only those who are fluent?  Do you count those who only speak a few words?  How do you measure fluency?  Get everyone in the world to take a test?

So, if you really need to know how many people speak English (not just native-speakers), check out the estimates listed on this page.
http://en.wikipedia.org/wiki/List_of_languages_by_total_number_of_speakers

Why should I study English?

Three-quarters of the world's mail, telexes and cables are in English.

More than half of the world's technical and scientific periodicals are in English

English is the medium for 80% of the information stored in the world's computers

Over 700 million people, speak English, as a foreign language.

http://www.englishlanguageguide.com/english/facts/stats/

 It does appear that the number one reason that people should study English is not that it is the most used language in the world but because it does give you access to more information than any language in the world.