Apple said it sold more than 300,000 iPads in the US on its first day of availability, a figure in line with predictions of some analysts but fewer than others expected.
Apple said the sales figures for the iPad included pre-ordered shipments of the table computer and purchases at retail stores around the United States.
The Cupertino, California-based company also said iPad users downloaded more than one million applications at Apple's App Store and over 250,000 electronic books from Apple's iBookstore during the first day.
"It feels great to have the iPad launched into the world - it's going to be a game changer," Apple chief executive officer Steve Jobs said in a statement.
"iPad users, on average, downloaded more than three apps and close to one book within hours of unpacking their new iPad," Mr Jobs said.
Apple did not release sales estimates ahead of the release of the iPad and analysts had been mixed on their expectations for the touchscreen multi-media device.
Most analysts had predicted Apple would sell between 300,000 and 400,000 iPads by the end of the weekend.
The Wall Street Journal quoted Piper Jaffray analyst Gene Munster, however, as saying he expected sales of between 600,000 and 700,000 units.
Credit Suisse, which had provided a rough estimate of iPad sales of 400,000 to 500,000, described the 300,000 figure as a "solid number for a single day of sales".
Credit Suisse estimated iPad sales of 4.8 million units in 2010 and 8.7 million units next year. Morgan Stanley analyst Katy Huberty forecast iPad sales of six million units this year.
The iPad allows users to watch video, listen to music, play games, surf the web or read electronic books. It runs most of the 150,000 applications made for the iPod Touch and the iPhone.
The model that went on sale last Saturday features Wi-Fi wireless connectivity, while a model offering both Wi-Fi and 3G cellular connectivity will be released in late April.
The cheapest iPad model, with Wi-Fi connectivity and 16GB of memory, is $499 while the most expensive - which includes 3G connectivity and 64GB of memory - costs $829. The iPad has a 24.6-centimetre colour screen and resembles an oversized iPhone. It is 1.3 centimetres thick, weighs 0.7 kilos and comes with 16, 32 or 64 gigabytes of memory.
Wi-Fi and 3G models will be available in Australia, Britain, Canada, France, Germany, Italy, Japan, Spain and Switzerland in late April.
Apple has been pushing the iPad's abilities as an e-book reader and analysts have described the tablet computer as a potential rival to Amazon's Kindle.
Unveiling the iPad in January, Apple CEO Mr Jobs hailed it as a "revolutionary" device and said he was taking a gamble by trying to carve out an entirely new product category between the laptop computer and the smartphone. Reviewers have been mixed on whether the iPad will be a smash hit like the iPod, which controls over 70 per cent of the market for MP3 players, or the iPhone, which completely transformed the smartphone arena.