I had a test yesterday. There was a question about fraction number and it's way of writing. What is the right form of spelling of "1/2 ton"? A half of ton, half of a ton or half a ton?
You can say either:
half a ton
one half ton
Without an "of" in "1/2 ton", you can't say "half of a ton". "half of ton" is wrong because "ton" requires an article.
It depends on the context. Normally, you would probably say "half a ton", as in
The ingot weighs half a ton.
However, if "1/2 ton" is an adjective, then you would write
You need a forklift to move that half-ton ingot.