How many iPads did Apple sell last quarter?

Chart: PED

FORTUNE (Vang Vieng, Laos) -- Sales of Apple's (aapl) iPad grew from zero to 7.3 million units in 2010 and doubled in 2011 to 15.4 million.

According to our most bullish independent analysts, they doubled again in calendar 2012.

According to the most bearish professional -- Argus Research's Jim Kelleher -- they grew (once you factor out 2011's extra week) only 3%.

That seems unlikely. It's hard to say how much the introduction of the iPad mini cut into sales of the larger iPad or into Apple's profit margins, but most signs -- from New York City's launch-day queues to the spike in mobile add impressions -- suggest that Apple has another hit on its hands.

The estimates among the 56 analysts we've heard from so far -- 31 pros and 25 independents -- range from Kelleher's 16.8 million to the indy-high 32 million submitted by the Braeburn Group's Dennis Hildebrand.

The pro's consensus estimate is 22.8 million; the indies' is 25.5 million.

The median estimate among all the analysts we polled is 24 million. That represents 67% year-over-year growth if you factor out 2011's extra week and 55% if (for shame) you don't.

Below: The individual analysts estimates, with the pros in blue and the indies in green. We'll find out who was closest to the mark when Apple reports its earnings for fiscal Q1 2013 on Wednesday Jan. 23.

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