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New Largest Known Prime Number Has More Than 23 Million Digits

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Prime numbers come in all sizes: They go down to single digits and grow infinitely larger. But calculating the exact quantity of the largest prime numbers in existence takes serious time and effort. Now, thanks to help from a volunteer and his computer, the Great Internet Mersenne Prime Search (GIMPS) has identified the newest largest prime number we know of.

The prime number has 23,249,425 digits, surpassing the previous record holder by 1 million digits. It can be written as 277,232,917-1 or M77232917. Like other prime numbers, the quantity can only be divided by one and itself. But unlike some smaller primes, this one joins a special category called Mersenne primes.

Mersenne primes are found by calculating numbers to the second power and subtracting the value of one from the total. Only 50 prime numbers have been found this way, and a lot of computing power is required to uncover them.

Since 1996, GIMPS has been crowdsourcing computers to discover larger and larger prime numbers. Anyone can download their program and dedicate their unused processing power to churning out algorithms in search of the next record breaker. Volunteers whose computers successfully identify a new prime number are eligible for a cash reward of up to $3000.

The most recent winner was Jonathon Pace, a 51-year-old electrical engineer from Tennessee. His computer calculated the number M77232917 on December 26, and its prime status was independently verified by four separate computers.

GIMPS is constantly outdoing itself, with the previous largest prime announced just two years ago. If you'd like to join the effort, their prime-hunting software is free to download. But don't expect instant results: Pace was volunteering with GIMPS for 14 years before his altruism paid off. 

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How Much Does a Missing Comma Cost? For One Dairy in Maine, $5 Million
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Copy editors aren’t the only ones who should respect the value of the Oxford comma. Since 2014, a dairy company in Portland, Maine has been embroiled in a lawsuit whose success or failure hinged on the lack of an Oxford comma in state law. The suit is finally over, as The New York Times reports, and die-hard Oxford comma-lovers won (as did the delivery drivers who brought the suit).

The drivers’ class action lawsuit claimed that Oakhurst Dairy owed them years in back pay for overtime that the company argues they did not qualify for under state law. The law reads that employees in the following fields do not qualify for the time-and-a-half overtime pay that other workers are eligible for if they work more than 40 hours a week:

The canning, processing, preserving, freezing, drying, marketing, storing, packing for shipment or distribution of:

(1) Agricultural produce;

(2) Meat and fish product; and

(3) Perishable foods

Notice that it says the “packing for shipment or distribution” and not “packing for shipment, or distribution of.” This raised a legal question: Should dairy distributors get overtime if they didn’t pack and distribute the product?

The case eventually made its way to the United States Court of Appeals for the First Circuit, which ruled that the lack of comma made the law ambiguous enough to qualify the drivers for their overtime pay, overturning the lower court’s verdict that the state legislature clearly intended for distribution to be part of the exemption list on its own.

In early February, the company agreed to pay $5 million to the drivers, ending the lawsuit—and, sadly, preventing us from ever hearing the Supreme Court’s opinions on the Oxford comma.

Future delivery drivers for the dairy won’t be so lucky. Since the comma kerfuffle began, the Maine legislature has rewritten the statute. Instead of embracing the Oxford comma, though—as we at Mental Floss would recommend—lawmakers decided to double down on their semicolons. It now reads:

The canning; processing; preserving; freezing; drying; marketing; storing; packing for shipment; or distributing of:

(1) Agricultural produce;

(2) Meat and fish products; and

(3) Perishable foods.

Come on, guys. What do you have against the serial comma?

[h/t The New York Times]

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Flights Grounded After World War II Bomb Discovered Near London City Airport
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Dan Kitwood, Getty Images

London City Airport grounded all flights on the night of February 11, after a World War II bomb was found in the neighboring River Thames, The Guardian reports.

The half-ton bomb was revealed Sunday morning by development work taking place at the King George V Dock. Following its discovery, police set up a 702-foot exclusion zone around the area, closing local roads and shutting down the London City Airport until further notice. According to the BBC, 261 trips were scheduled to fly in and out of London City Airport on Monday. Some flights are being rerouted to nearby airports, while others have been canceled altogether.

The airport will reopen as soon as the explosive device has been safely removed. For that to happen, the Met police must first wait for the river's tide to recede. Then, once the bomb is exposed, they can dislodge it from the riverbed and tow it to a controlled explosion site.

The docks of London’s East End were some of the most heavily bombed points in the city during World War II. Germany’s Blitz lasted 76 nights, and as the latest unexpected discovery shows, bombs that never detonated are still being cleaned up from parks and rivers more than 75 years later.

[h/t The Guardian]

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