There are far more physical quantities than in the table above. All other physical quantities are known as derived quantities. Both the quantity and its unit are derived from a combination of base units, using a defining equation.
Examples of derived units:
So, from the defining equation, the unit of velocity is $m s^{-1}$ or $m/s$
So, from the defining equation, the unit of velocity is $m s^{-2}$ or $m/s^{2}$
Some other derived units include: Newtons, Watts, Joules, Volts and Ohms. There are special names given to particular combinations of base units. For example:
So, from the defining equation, the unit of force is is $kg \cdot m \cdot s^{-2}$. This is given a special name: Newtons (N).
All units are derived from base units using equations. This means that in any correct equation, the base units of each part must be the same. When this is true, the equation is said to be homogenous. Homogenous means 'composed of identical parts'.
The number of significant figures you give your answers in depends on the precision of the numbers you use in the calculations. Your answer cannot be more precise than the the data you use. If some of the figures are given less precisely than the others, then round up to the lowest number of significant figures.