Approximate measure

An approximate measure is a numerical estimate of a quantity that does not claim exact precision. It communicates a value while allowing for uncertainty, rounding, or limited measurement resolution.

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Rounding: Replacing a number with a nearby value having fewer digits or a simpler form. Rounding turns detailed readings into simpler approximate measures.
Measurement: The process of assigning a value to a quantity by comparing it with a unit or standard. An approximate measure is one possible outcome of measurement.
Estimation: The process of inferring a value from incomplete information, calculation, or judgment. Estimation produces useful approximate measures without requiring direct exact measurement.
Exact number: A number whose value is fixed without measurement uncertainty, such as an integer count or a defined conversion factor. An exact number contrasts with an estimate whose value is not claimed to be exact.
Significant figures: Digits in a measured or calculated value that convey its precision under stated conventions. Displayed digits can make an approximation appear more precise than its evidence supports.
Instrument resolution: The smallest change in a quantity that a measuring instrument can distinguish or display. Resolution sets a practical limit on the precision of an instrument's reported measure.
Physical quantity: A property that can be quantified, such as length, mass, duration, or temperature. The measure estimates a quantity rather than defining the property itself.
Order of magnitude: A value expressed by the nearest power of ten, indicating its broad scale rather than fine detail. Order-of-magnitude estimates answer scale questions with deliberately limited precision.
Exact measurement: A measurement that determines a quantity without error or uncertainty; physical measurements ordinarily cannot achieve this ideal. The ideal clarifies why empirical measures are normally approximate.
False precision: The appearance of unwarranted exactness created by reporting more digits than evidence or methods justify. Approximate measures invite false precision when their limits are hidden.