Hi Robin, I would suggest: 1. You altogether defeated the champion — I think this is ok, although a little awkward. In colloquial english, we would say, "You totally defeated the champion" — it's a fun way to say it! :) 2. These cost $100 altogether — perfect, great job 3. Don't forget to bring my necklace back and my handbag all together. — Gary is correct that this is not a great sentence. Depending on the intention, I would suggest: A) "Don't forget to bring my necklace and my handbag back" (suggests both the necklace and handbag need to be returned) B) "Don't forget to bring my necklace back, and also bring my handbag." (suggests only the necklace is being returned)

I'm not sure of your question... 1. Is perhaps more an American usage. I would not use altogether like that. 2. is fine. 3. Is not a natural sentence. I guess someone might say it, but to me it sounds like someone said one sentence, then added another bit as an afterthought. You could use 'all together' for two things, but it would probably be more natural to use 'both'.