After losing marks in an exam due to significant figures, I have decided to clear up all my doubts about this concept. But since my teacher hasn't been very helpful, I've decided to post my question here. I understand the rules for significant figures in both single-step multiplication/division and addition/subtraction calculations, but I am uncertain about what to do with them in long sequences of calculations, especially ones involving both types of arithmetic calculations. Based on my brief research on the Internet, I have found that intermediate answers should not be rounded as this would lead to accumulated error. Instead one should take a few more digits in the calculation process than required in the final answer and then round off at the end. But what I don't understand is, how do we decide how many significant figures to round off to at the end? Do I use the rule for multiplication/division (as many significant digits as the data with the least significant digits) or the rule for addition/subtraction (as many decimal places as the data with the least decimal places)? Any help will be appreciated. Thank you.