The number of backlinks that you’ll need will depend on the quality of the backlinks you get. For example, if you a get a do follow link on the homepage of google, you’ll be in the first position for that SERP as soon as the index next updates. That’s not very realistic though, those kind of links aren’t readily available. You’ll probably need hundreds, or even thousands of quality backlinks of all different kinds of quality to come close to the number 1 spot.
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