Significant Figures: digits that express some feeling of certainty and estimation to a measurement.. 1.44 cm has 3 significant figures.. the 1.4 shows certainty that it is at least 1.4, and the last 4 is the estimation...
Exact Number: values known with 100% accuracy.. often times conversion factors or counts of objects.. 16 ounces per pound is an exact number because there can be no more or no less ounces to make 1 pound, it must be EXACTLY 16oz... they are said to have infinite significant figures
This video goes over the definition of and how to measure significant figures and how to tell the difference between sig. figs. in estimation and in exact numbers.
