Significant figures are digits read directly from the instrument plus one more digit which is by the observer?

Significant figures represent the precision of a measurement, consisting of all the digits that are known with certainty plus one estimated digit. The digits read directly from the instrument are considered significant, while the additional digit reflects the observer's estimation of uncertainty. This practice helps convey the reliability of the measurement and is crucial in scientific calculations to ensure accuracy. Properly using significant figures allows for clearer communication of the precision of data.