Ten-plus million digits? The ever-changing world of facts

What would we do without the Internet...

I mentioned recently that a quick check on the current population of Burundi--the subject of a French lesson--showed that there were way more people there than even the (fairly recent) teacher's guide suggested.  That lined up with the fact that we were heading for 7 billion people on Earth by the end of last month.

Today's math history lesson was about the Sieve of Eratosthenes, and the hunt for very large prime numbers.  John Tiner's 2001 book Exploring the World of Mathematics mentioned that the largest one discovered to date was over 4 million digits long, which would take about a thousand pages to print out.

On a hunch that that fact too might have been updated, I looked up "Largest Known Prime Number."

Yes, the 4-million-digits longest prime was correct in 2001. 

But as of 2008, we are up to a number that is 12,978,189 digits long.

And you thought your ID numbers were hard to learn.