## Now we’re closer than ever to solving a 50-year-old math problem.

In a crowdsourced effort, thousands of people from around the world have helped land the discovery of one of the largest known prime numbers, comprised of about 9.3 million digits, or 9,383,761 to be exact.

According to *New Scientist*, a discovery like this would take centuries using a single computer, but thanks to the thousands of collaborators, the prime number was discovered in just eight days.

**SEE ALSO: Can You Solve This Centuries-Old Math Problem?**

**SEE ALSO: Can You Solve This Centuries-Old Math Problem?**

Volunteers took to the PrimeGrid website, where they were able to contribute spare computing power to calculate the lengthy number.

Even with over nine million digits, the new prime number doesn’t make it into the top five largest known prime numbers — it takes seventh place. Incredibly, the largest known prime number, called a Mersenne prime number, contains a whopping 22 million digits.

However, what’s neat about this new discovery is that the 9.3-million-long prime number brings us closer than ever before to figuring out a decades-old math problem: the Sierpinski problem.

The problem was identified back in the 1960s by Polish mathematician Waclaw Sierpiński. In short, the challenge is to find the smallest possible number that meets the following set of criteria — the number must be positive, odd, and fill in for the place of k in the formula k x 2n + 1. The tricky part is that all of the integers must be composite (not prime numbers), as *ScienceAlert* explains.

Currently, the lowest known Sierpiński number is 78,557, but with the discovery of the new prime number, mathematicians may be en route to discovering even smaller ones.

Since the problem’s debut in the 60s, mathematicians have found six possible candidates for the smallest Sierpiński numbers: 10,223; 21,181; 22,699; 24,737; 55,459; and 67,607. So far, none of them have been confirmed as Sierpiński numbers, but the newly discovered prime number has eliminated one of the six candidates — 10,223.

Curious what the longest-ever prime number looks like written out? Check out *Numberphile*’s video below.

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