A large number of math type equations and functions in a python module
Am I doing this right?


Almost.


  as in is this the best practice to code utility functions? 


These aren't "utility" functions.  They appear to be central to your app.  There are rarely "utility" functions in any app.  

What we used to call "utility" functions are almost always part of a standard library. 


  should I be separating all the mini calculations into separate functions


Yes.


  but then have to deal with 200 functions instead of the current 50?


You still have the calculations.  You're just giving them names and keeping them separate.  Giving them separate names makes them more reusable, easier to test and easier to find.

The most important thing here is to avoid creating a (nearly) useless class who's only job is to contain a bunch of functions.

Your code uses no instance variables and simply uses another function that happens to be in the class.  Both of these could be @staticmethod method functions.

There's no reason -- in Python -- to create a class unless you have instance variables and a change in state of some kind.

[In Java, you must often create "all-static" classes because there's no other place to put stateless math like this.]

You can simply put these functions into a simple module and avoid the class definitions.