Quote:
Originally Posted by Jellby
For me a trillion has always been 10^18, so making it 10^12 is certainly making it a lot smaller  |
The actual number is even smaller. The first three digits indicate that it is a book. They are always 978 (can also be 979 in the future). The last digit is a checksum digit, so it leaves only 2*10^8 possible numbers. Considering that the ISBN includes a country code and a publisher code, so you cannot use every number, it probably leaves only 2*10^7 usable ISBN's. Twenty million books is not that much.