Unlike most physical quantities, particle number is a dimensionless quantity.

Being a dimensionless quantity, it has constant numerical value in all systems of units.

There are infinitely many dimensionless quantities and they are often called numbers.

Rewrite the system of equations in terms of their new dimensionless quantities.

Certain dimensionless quantities of some importance are given below:

For a gas, the activity is simply the fugacity divided by a reference pressure to give a dimensionless quantity.

Information capacity is a dimensionless quantity, because it refers to a count of binary symbols.

Effectiveness is dimensionless quantity between 0 and 1.

However atomic weight is a dimensionless quantity, and cannot take the units of grams per mole.

Because its numerical value is the same under all possible systems of units, it is a dimensionless quantity.

Although the radian is a unit of measure, it is a dimensionless quantity.

For the purposes of the experimenter, different systems that share the same description by dimensionless quantity are equivalent.

The mass number is a dimensionless quantity.

The notation is mathematically flawed because the unit "%" can only be used for dimensionless quantities.

Specific gravity, as it is a ratio of densities, is a dimensionless quantity.

This list contains selected positive numbers in increasing order, including counts of things, dimensionless quantity and probabilities.

Other examples of measures that are not dimensionless quantities are as follows:

Hence, the new forcing function F is made to be dependent on the dimensionless quantity τ.

In electrical power systems it is a dimensionless quantity defined at the receiving end of a transmission line as:

The group identity 1, the dimension of dimensionless quantities, corresponds to the origin in this vector space.

The dimensionless quantity so obtained may be multiplied by 100 to express ovality as a percentage.

They cancel out, leaving a dimensionless quantity.

By convention, activity is treated as a dimensionless quantity, although its actual value depends on customary choices of standard state for the species.

In general, dimensionless quantities are scale invariant.

It is a dimensionless quantity and is an indicator of the performance of the engine or vehicle.