"I am ten years old."
I know that the pronounciation 'Juusai' is right, can anyone tells me if the pronounciation of 'Juutoshi' is also OK? Thanks.
Afaik no. Some Japanese kanji have two, or more, meanings. The pronunciation is "sai". Toshi is another meaning/pronunciation of this symbol. This is yet another poorly constructed exercise.
How come its "Ju sai desu" instead of "Ju desu?" When saying fourteen (example) its "Ju yon desu."
H A L P M E P L E A S E
さい (歳 or 才) is the counter for age, so it means "years old". So, "I'm 10 years old" is 十さいです and "I'm 14 years old" is 十四さいです
Of course, in English, it's very natural to leave out the "years old" and just say "I'm 10". However, this doesn't transfer over to Japanese. You must have さい if you are talking about someone's age.
I don't say this to be rude, but 才 (which is different from the katakana オ "o", though they look very similar in my font) is generally only used by children, i.e. those who have yet to learn to write the "full correct" version which is 歳 ;)
My understanding is that years for age is always "sai." I'm baffled this is saying "toshi." Wouldn't that mean, "I'm 10 years" rather than "I'm 10 years old."