Recently a very strange result has been making the rounds. It says that when you add up all the natural numbers

1+2+3+4+...

then the answer to this sum is -1/12. The idea featured in a Numberphile video (see below), which claims to prove the result and also says that it's used all over the place in physics. People found the idea so astounding that it even made it into the New York Times. So what does this all mean?

Prime numbers — we've often reported on them here on Plus, and in particular we've followed the progress of the Great Internet Mersenne Prime Search. It's one of the longest-running grassroots distributed computing projects. Users donate their computing power to search for these special type of primes, and of course the goal is to find bigger and bigger ones. The latest prime to be discovered by the project is 2^57,885,161-1.