No, "twelve thirty" is not hyphenated when written out as a time. It is typically written as two separate words. However, if used as a compound adjective before a noun, it may be hyphenated, such as in "a twelve-thirty appointment."
No, the word "thirty first floor" is not hyphenated.
at twelve thirty
Any two or three word adjective should be hyphenated ONLY when used as an adjective. Example, "It was his thirty-second birthday." "There was a thirty second delay in rebroadcasting Carl's speech."
Yes, "thirty-fifth" is hyphenated when used as a compound adjective before a noun or as a noun itself. For example, you would say "the thirty-fifth anniversary." However, when it stands alone as a noun, it can be written without the hyphen as "thirty fifth."
Thirty-two. Twenty plus twelve is thirty-two.
No. I cannot see any hyphen.
Twelve and thirty-two hundredths.
Twelve thirty in the afternoon would be most correct. You cannot say twelve thirty o'clock. You only say o clock when you don't have any minutes over.
That is the correct spelling (hyphenated) for the fractional parts "thirty-seconds" (i.e. multiples of 1/32).
Twelve
No. The term "twelve year old" is a noun (someone who is 12). It can be an adjective, but should be hyphenated, as in twelve-year-old cat. *The Chicago Manual of Style suggests that both nouns and adjectives should be hyphenated. Other styles may differ.
35 is spelled "thirty five". When used as an adjective, it should be hyphenated, as in "I had thirty-five marbles."