How to calculate Reynolds number?
One way is to see what the following NASA links have to say about it and possibly using the calculator they have at the bottom of either page.
https://www.grc.nasa.gov/WWW/K-12/airplane/viscosity.html

The similarity parameter for viscosity is the Reynolds number. The Reynolds number expresses the ratio of inertial forces to viscous forces. From a detailed analysis of the momentum conservation equation, the inertial forces are characterized by the product of the density $\rho$ times the velocity $V$ times the gradient of the velocity $dV/dx$. The viscous forces are characterized by the viscosity coefficient $\mu$ times the second gradient of the velocity $d^2V/dx^2$. The Reynolds number $Re$ then becomes:
$$Re = (\rho \cdot V \cdot dV/dx) / (\mu \cdot d^2V/dx^2)$$
$$Re = (\rho \cdot V \cdot L) / \mu$$
where $L$ is some characteristic length of the problem.

and

The dynamic viscosity coefficient divided by the density is called the kinematic viscosity and given the Greek symbol $\nu$
$$\nu = \mu / \rho$$
$$Re = V \cdot L / \nu$$
The units of $\nu$ are length^2/sec.

https://www.grc.nasa.gov/WWW/K-12/airplane/reynolds.html

The Reynolds number expresses the ratio of inertial (resistant to change or motion) forces to viscous (heavy and gluey) forces.