How many significant figures are in 74.30?

Answer 1

Answer: four. All written decimals are significant (even if it is 0).

However if you have a physics computation where one number turns out to be x = 2.0 (2 significant figures) and the other turns out to be y = 37.15 (4 significant figures), then to compute the product x*y you should take the least of these significant numbers you are using. Hence, you will find that

x*y = 2.0 * 37.15 (= 74.30) = 74 (rounded to the nearest number with 2 significant digits only.)

So, it depends on the context you are using this number in.