8/10, and, as mentioned in the explanation on the second blog post, I did feel like I was giving ridiculously wide ranges for some of them, turns out I wasn't ridiculous enough - as one commenter points out, a more interesting exercise might be to do the same but with 50% ranges - then the simple solution of "make an estimate and put 3 orders of magnitude each side" doesn't help.

Also, the length of the coastline of the Pacific, which is one of the ones I got right is, as HonoreDB and several commentors on the blog post have pointed out, undefined - it depends what length ruler you use.