Is the sentence "I don't know what is the point of doing that" correct?

Question

Is the sentence "I don't know what is the point of doing that" correct?   

Thanks! - Hiya Raymond, China

Answer

The short answer

The short answer to your question is no. Your sentence “I don’t know what is the point of doing that” is not correct. This sentence should be formed like this:  

• I don’t know what the point of doing that is.

Understanding why

Your original sentence ("I don't know what is.....") has this question embedded in it:

• What is the point of doing that? 

As a question, by itself, this is perfectly formed, because the verb “is” and the original subject, “the point of doing that,” have been “inverted,” so that now the verb “is” comes first.  

However, when a question like this is embedded in a larger sentence, the rule is that the subject and the verb go back to their original positions, as in:

• I don’t know what the point of doing that is.

By the way, this error, using the inverted verb-subject rule when it doesn’t apply, is very common!