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I would like to be able to call the Quantity function with a null unit so that it returns the original dimensionless value. For example,

Quantity[3.0,"NoUnits"]

would return 3.0. Is there a dimensionless unit?

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  • $\begingroup$ If it isn't there, I assume you could just add a definition to Quantity. What use of that do you have in mind? $\endgroup$ – Rojo Dec 21 '12 at 21:34
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    $\begingroup$ @Rojo: I run Monte Carlo simulations which output huge quantities of data with varying dimensions, so I created a data dictionary which describes each data type, including the units. When the simulation results are loaded into Mathematica, I use the data dictionary to attach units. However, some of the data types are dimensionless and rather than having a special "dimensionless" case for the code that calls Quantity, I'd rather have Quantity handle it. $\endgroup$ – Cassini Dec 21 '12 at 21:38
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I believe you can use "DimensionlessUnit" to get the desired result:

Quantity[3, "DimensionlessUnit"]
3

(note this is the unit produced by QuantityUnit on a dimensionless value):

QuantityUnit[3]
"DimensionlessUnit"
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  • $\begingroup$ Deleting my answer, +1 $\endgroup$ – Rojo Dec 21 '12 at 21:58
  • $\begingroup$ Perfect! Thanks! $\endgroup$ – Cassini Dec 21 '12 at 21:58
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    $\begingroup$ @Rojo: I still found your answer helpful because it forced me to (finally) learn something about unprotecting symbols. I think you should keep your answer. $\endgroup$ – Cassini Dec 21 '12 at 22:00

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