Phrase Match Google Results Inconsistency

So while doing some KW research, I used phrase match for a KW and saw that a 5 word KW had about 300,000 results, which I thought was pretty odd. So I went ahead and starded navigating through all the results pages up to number 9 and when I was in number 9, the number of results dropped to a total of 71, instead of 300,000 and there where no more pages to navigate.

So what´s my competition, 300,000 or 71??????????????????'

thanks

 

Here is a good explanation and a video on this;

supremetechs.com/wordpress/2009/07/30/google-search-results-change/