Basically.
I've always learned it/done it sort of like the first way (if I am being picky, mind you... not so much just blabbing on a forum or whatever). General rule is if it's one or two-digit numbers, spell it out. Any more, make it numerical.
Pretty sure there is a "legit proper way" and my mind is really trying to pinpoint it but I am half tired and it's been too long for me to have to worry about it.