that's the size of the improvement that an online army of collaborating mathematicians has alredy made to a groundbreaking proof involving pairs of prime numbers, which was first annoounced just a few weeks ago.
The work relates to a longstanding problem called the twin prime conjecture. A prime number can only be divided by 1 and itself, and twin primes are those just two numbers apart. The conjecture, put forward in 1849, say there are an infinite number of these pairs, but no one has managed to prove or disprove it.