The purest enjoyment of life - be a RailFan.

From another source the data varied on different parameters:
click here Data source: Ethnologue: Languages of the World, 15th ed. (2005)
Mandarin Chinese NATIVE: 873 million
2nd: 178 million
TOTAL: 1.051 billion,
Hindi NATIVE:...
more...

370 million
2nd:120 million
TOTAL: 490 million,
Spanish NATIVE: 350 million
2nd: 70 million
TOTAL: 420 million,
English NATIVE: 340 million
TOTAL: 510 million.
click here
1Mandarin
Number of speakers: 1 billion+,
2 English
Number of speakers: 508 million,
3 Hindustani-(Hindustani is the primary language of India’s crowded population, and it encompasses a huge number of dialects (of which the most commonly spoken is Hindi). While many predict that the population of India will soon surpass that of China, the prominence of English in India prevents Hindustani from surpassing the most popular language in the world.)
Number of speakers: 497 million,
4 Spanish
Number of speakers: 392 million