What is the importance of significant figures when working with measurements and calculated quantities based on actual measurements?

Three

When you make a measurement using significant figures, you record the numbers you definitely know from the instrument, plus an estimate of the last digit.

Significant figures are important in measurement because they determine how accurate a scientific claim can be. There always has to be a small amount of uncertainty in an answer, because no...

there are 2 significant figures

In any measurement, the accurately known digits and the first doubtful digits are called significant figures.