= Dimensionless quantity
{title2=$\operatorname{dim}q=1$}
= Dimensionless
{synonym}
A dimensionless quantity has zero exponent for every base physical dimension. It can be formed by dividing two quantities with the same dimensions, such as $x=r/R$ or $q=m/M$. Its value is independent of the choice of units for those dimensions. The quantities $GM^2/R$ and $Lt$ both have dimensions of energy, so $RLt/(GM^2)$ is dimensionless. A <dimensionless variable> is such a quantity used as an unknown or independent variable in an equation.
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