I know I wan't consistent with NUMBERam and simply a.m. But I'm lazy and I think it's obvious that "am" after a number is not a form of the verb "to be" while on its own that's not so clear. So I fudged.
I'm currently reading a book on punctuation. Grammar book publishers seem to have a law that insists on punny titles: "A Dash of Style," "You Have a Point," "Lapsing Into a Comma," etc. Therefore I found it rather strange that the book has a section entitled,
"What your use of the colon says about you."
How I use my colon is between me and my proctologist, I think.