Question

define an example for dimensional less physical quantity having unit
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Answer 1

Answer:

it is not possible the physical quantities which does not have dimensions also does not have the unit

Answer 2

Explanation:

All pure numbers are dimensionless quantities, for example 1, i, π, e, and φ. Units of number such as the dozen, gross, googol, and Avogadro's number may also be considered dimensionless.

hope it helps.