Can I use a pen on the sat test booklet ?
Pens (along with highlighters, colored pencils and other non-#2-pencil writing utensils) are prohibited. The only way you will be able to use one is if your proctor fails to enforce that rule. If you have a documented learning issue that means you really need to use a pen to mark in your booklet, you can apply for an accommodation. However, I have never heard of anyone having that particular accommodation. My advice would be to practice doing your marking with a #2 pencil.