The spelling "thirtieth story" is the correct written form of "30th story" (of a building).
*The UK term for a building level is spelled storey.
thirtieth
Thirtieth.
The ordinal number 30th is spelled thirtieth.
Thirtieth.
The ordinal number 30th is spelled thirtieth.
"not thirtieth." There really isn't a precise single-word antonym for it.
The thirtieth sultan of the Ottoman Empire was Mahmud II.
Thirtieth means being one of 30 equal parts. So one thirtieth is 1/30 and 1/30 as a decimal is 0.0333...
Thirtieth.
adjective
Thirtieth
Chewbacca is how you spell it.