ik significant figures matter in both science and maths, but if the question doesn't specify how many decimal places to use and in your answer you use 2 decimal places instead of 3 like as shown in the worked solutions, do you get marked down???
no they would still accept it as long as you rounded it correctly. But to be safe just write the entire decimals out, it doesn't take too long and you guarantee yourself the marks for these types of unspecified rounding questions.