On photo day at school, if I don't like my photo, I take ask the photographer to take another picture. Similarily, if you write a math test and you don't think the result reflects what you know, then I would expect you to rewrite it!
If your test score is less than 60% you will have an INC as your grade for that unit. I know that you understand more than 60% of the unit, so go ahead and retest:)
You can retest as many times as you need to until you believe the result matches what you know.
You should be aware that I always take the latest test score as your new score. That means that if your scores goes up, your mark goes up. The reverse is also true. So make sure you are ready. After you have written the retest, you will always be given the chance to ask me to mark it or NOT to mark it if you don't want me to mark it. (IF someone with less than 60% retests, the better mark between first test and second test will always be taken.)
Don't forget to sign out a retest licence prior to writing the test. This can be found where marks are posted my classroom.