When does Google update PR?

When does Google update PR? Can someone help me please, I heard from some people it was every 4 months, but a article I read said that you can get a PR of 4 in 30 days. So please help me

every 3 to 4 months i have heard in many forums and from senior posters

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hyderabad l uttarakhand
India Forum l Social Bookmarking l Social Networkiing l Free Directory

I think it happens in once every 3 months. yes you can get a PR4 in a month if you have enough links from PR4+ at least 10 PR5+ links and more than 1500 backlinks. You cant get a PR4 in less than a month becouse it takes time to google to update links and all depends of how long banklink lasted too.

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In my experience every 3 or 4 months PR is updated, lastest updated was weeks ago

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I think they are doing it all the time..
Its just that they "show" the changed PR every 3-4 months

Google updates its Page Rank calculation all the time and keeps it in the data servers. But it updates the PR toolbar only once in 3 months. This is what i have learnt from other posters. Only the google toolbar gets the info. first.

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Passion to read

People always say it is 3-4 months, but it always seems longer :P. There is no defined point, as far as I know, but historically that is the time line.

Page rank updates occur quarterly. The only way you would know when the next on would be is if you worked with google. The way i find out when i get the itch is i search pr update in google.... if you click the first result that comes up it lists previous updates as well as estimates the next update.

They start PR update with back links updating then updating their data servers and at end toolbar.

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one or two month ,i heard from some webmaster