Grandson, when I was born, there were no less than 2,005 times... Hum. One billion people, I think. Thank you calculator! In the world.

— How come my old grandfather makes such en error?

_{Note: people who instantly gets the knowledge tag will benefit from it a lot. You are several in this website to have it for sure. I think with more research from those who don't have it, you still can figure out the puzzle and that'd be even more impressive!}