SAT Subject test unanswered questions

Hello, I’m taking the SAT Subject test Math 2 and Chemistry and I have studies all I could. But now I I know that I will leave a bunch of questions Blank in the test just because I didn’t learn the some of the topics that the tests prep have shown me. I just want to ask what would be the best strategy. do I get point deducted from leaving many questions blank? or is it best to just answer what I know and leave blank the other ones instead of random guesses (not educated guesses)? I saw somewhere that people were talking about leaving 10 to 0 blank questions to get around 600 or something and I am very confused. Help!!!