700 million people is not the number of people who speak Mandarin as their mother tongue.
According to a survey in PRC:
- 53 per cent of the population can communicate with the language known as putonghua.
-
only 18 per cent of those surveyed speak Mandarin while talking to the family members, while 42 per cent speak at school, work or play.
http://www.chinadaily.com.cn/english...ent_403419.htm
18% of Mainland Chinese makes 235 million (of 1,306 million total); we also need to add those in Taiwan and Overseas, but total should be still well below 300 million.