How many independent clasues does this sentence have? Since I didn't have homework, I went to the mall with my friends, but I forgot to study for my test.

3 independent clauses

Explanation:

Independent clauses is defined as a group of word that consists of a subject as well as a verb. And the group of words should always express a complete though. An independent clause is a full sentence with a meaning containing verb and a subject.

In the context, the sentence contains 3 independent clauses:

-- I didn't have homework

   Here, 'I' is the subject and 'didn't' is the verb.

-- I went to the mall

   Here, 'I' is the subject and 'went' is the verb.  

-- I forgot to study

   Here, 'I' is the subject and 'forgot' is the verb.