Dimensionless quantity ($\dim q=1$)

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 $G{M}^2/R$ and $Lt$ both have dimensions of energy, so $RLt/(G{M}^2)$ is dimensionless. A dimensionless variable is such a quantity used as an unknown or independent variable in an equation.