+A **dimensionless quantity** is a number that stands free of any [physical unit](/wiki/Physical_Unit) or [dimension](/wiki/Dimension). It often arises as a [ratio](/wiki/Ratio) of like quantities, offering a pure comparison or scaling factor without dependence on the chosen system of measurement.
+## See also
+- [Unit](/wiki/Unit)
+- [Ratio](/wiki/Ratio)
+- [Constant](/wiki/Constant)
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