On a DMV written test, the number of questions and the percentage needed to pass will vary by state. Each state has its own licensing requirements, tests and guidelines. The best course of action is to call or stop by your local DMV. You can also check their website. They will be able to provide you with a drivers license manual which should cover all of the traffic rules and regulations that you will be tested on. It will also tell you the percentage needed to pass. The majority of DMVs require a percentage around the 80% mark to pass, but it varies by state. The average written test is between 25-40 questions.