Not even Professor Trelawney's divination class could have prepared us for this.

Harry Potter and the Half-Blood Prince, the penultimate chapter in J.K. Rowling's epic fantasy series that went on sale around the globe at 12:01 a.m. Saturday, sold an astonishing 6.9 million copies its first day in bookstores in the U.S. alone.

The sales numbers for the 672-page hardcover book easily smashed the record set by the previous installment, Harry Potter and the Order of the Phoenix, which raked in a whopping 5 million copies two years ago.

According to Harry Potter's U.S. publisher, Scholastic, Half-Blood Prince proved so popular among Muggles eager to catch up with the British wiz kid's sixth year at Hogwarts that books were flying off the shelves faster than a Nimbus 2000--at the rate of nearly 250,000 per hour.

"This is a cause for celebration, not just for Scholastic but for book lovers everywhere," said an ecstatic Lisa Holton, president of Scholastic's Children's Books.

Most booksellers offered Half-Blood Prince, which retails for $29.99, at steep 40 percent discounts to spur the record sales.

Amazon.com, for example, peddled the book for $17.99; advanced orders have kept it at the top of the best-seller list with 1.5 million copies ordered before Saturday, making it the online retailer's largest new product release ever.

As for brick-and-mortal booksellers, Borders announced that it had sold more than 1 million units of Half-Blood Prince in its first 48 hours at more than 1,200 outlets, the biggest sales weekend for any book it has sold, while rival Barnes and Noble moved 1.3 million copies during the same period.

Meanwhile, the Half-Blood Prince audiobook also set a record, selling 165,000 copies in its first weekend, according to publishier Listening Library. The 18-CD set retails for $75 and the 12-tape box is $50.

Putting those figures in perspective, in its first 24 hours Half-Blood Prince conjured up about $140 million in revenue even factoring in the discounts--that's nearly three times the entire weekend box office for Warner Bros.' reimagining of Roald Dahl's Charlie and the Chocolate Factory directed by Tim Burton and starring Johnny Depp as candy man Willy Wonka.

Still, despite speculation that Pottermania might eat into Charlie's golden ticket sales by pulling young'uns away from the multiplex, the film had a sweet opening, grossing $56 million and proving the two could indeed peaceably coexist. (Half-Blood Prince nearly matched the combined take for top 10 movies this weekend, which was about $153 million, per Exhibitor Relations.)

Thanks to Half-Blood Prince, Rowling was able to make a Gringott-sized deposit. The author, already the richest woman in Great Britain with a net worth estimated at $1 billion, made $36 million in royalties on Saturday--not a bad day's work. (That includes U.K. sales figures, which are hovering in the 2 million-copy range, according to Nielsen BookScan.)

To meet expectations for the book's demand, Scholastic announced an unprecedented first printing of 10.8 million books, while mega-chains like Borders and Barnes and Noble hosted more than 5,000 "magic parties" for tykes nationwide who lined up for hours waiting for the stroke of midnight to snap up the latest adventure.

And based on early notices, Rowling delivered. Half-Blood Prince, in which Harry once again faces the tragic death of someone close to him at the hands of Lord Voldemort, is said to be the author's darkest and most emotionally satisfying work to date. One reviewer even compared it favorably to J.R.R. Tolkien's classic Lord of the Rings trilogy.

Scholastic, meanwhile, is rushing to restock store shelves, increasing the print run by 2.7 million copies to keep pace with the phenomenal demand.

All told, factoring in sales figures from Harry Potter and the Half-Blood Prince, the number of Potter books sold in the U.S. alone now stands at a spellbinding 116 million copies.