From Förberedande kurs i matematik 1

We write the numbers in decimal form and then compare them. By using \displaystyle {1}/{10}\;=0.1,\quad {1}/{5}\;=0.2 and \displaystyle {1}/{3}\;=0.333..., we have

\displaystyle \begin{align} & -\frac{1}{2}=-0.5 \\ & \\ & -\frac{1}{5}=-0.2 \\ & \\ & -\frac{3}{10}=-0.3 \\ & \\ & -\frac{1}{3}=-0.333... \\ \end{align}

If we just remember that these are negative numbers, we can see directly that

\displaystyle \begin{align} & -\frac{1}{2}<-\frac{1}{3}<-\frac{3}{10}<-\frac{1}{5} \\ & \\ \end{align}