where do you see these "git numbers" ? git is not svn...
It is from github at the very top of the page where it says "#### commits ## branches ## releases ..." an example would be from your fork "git 566" is "commit fade2b74". And yes it is very confusing. 
COMMIT NUMBERS--
I usually refer to commits/builds by the commit number. It is at the upper left of the page. Commit numbers are sequential. The do not, however, help with git "checkout" commands, like the hash value on the upper right. I still do not understand git checkout syntax well, but I use the commit number when referring to a specific build between releases while posting.
--scryptr
To clarify, that is the commit count, not an index, and is a GitHub feature, nothing to do with git. This number is mostly useless as it can be invalidated in a number of ways. With git, generally we refer to a commit by the first 7 chars of the sha1 hash.
Example:
r69 -> 989737b6a5149f1539fa6783106dd755ebeaeb7c -> 989737b
THANKS FOR CLARIFICATION--
I use the commit number for its value as an index. I apprecate the information, I know that the programmer needs a specific point to grab the code. The reader needs a sequential number to see about where the stuff is between releases.
--scryptr
P.S. I think solo-mining is still broken with NeoScrypt. --scryptr
Do what you want, but so far as historical record goes, it's completely useless. I could squash the entire git history to 1 commit and that counter would go back to 1. Or rebase away some commits in the middle and reduce it by 500. Anyone who reads that number in the future may or may not wind up looking at the same commit (nevermind the fact that you'll have to manually count commits to find it). IMO, making up your own nomenclature only serves to confuse anyone trying to help themselves and thus is a detriment to the community. The SHA1 is right there to c/p.