Depends, if you are writing a thesis to be publish–two spaces correct. These days nobody realized that. Anon is right. If you gotta piss about spacing, moran.
Keep shit from running together. KEK. Not a publisher, typesetter, maybe didn't learn keyboarding aka typing. Opinion "needs to die."
Opinions are like assholes–and you fill the bill.
Numbers like history, changed for marketing reasons. Original Boomers, post WWII. 1945-1955. But, then there was the Korean, Vietnam, etc. So just thrown all in together.
I LIKE IT!
GFY