How to number the equations
As far as I can see, in mac system, Typora automatically number the equations in Math block . But in windows system, there is no automatically numbering function. whether it has automatically or not, we can always choose to use \tag{} and \nonumber to number or remove the number for certain equations.
How to cite the equations
If we want to cite the equations later, we can use \label{name} and \ref{label_name} to cite the particular equation. Of course, we need to add $ $ outsides.