Translation:I know there are how many stars in the sky.
I know how many stars there are in the sky or I know there are many stars in the sky???? The current version is nonsense in English.
it should be "I know how many stars there are in the sky." they just translated word for word from VNmese.
"tôi biết có nhiều ngôi sao trên bầu trời" would be the way to translate your second sentence.
The Duo translation is "I know there are how many stars in the sky" which IS NOT ENGLISH IDIOM. When you answer in English, Duo tells you that you are wrong.
I'm sorry I can't be much of help. I'm just translating for you folks to understand what was nonsense in English. so there is no real need for you to capitalize, I already know.
-t when elongated often sounds like -n just as -p often sounds like -m. It's very common in songs.
Ha, ha two years later, same same with me. I thought it was "I am the ocean that knows..."