Formulas are used to perform mathematical operations within app. It works at the FRONT of you app. Mobsted platform supports all arithmetical math functions and all MathJS formulas.
You can use Math formulas at ANY ELEMENT on the platform. For example  on Screens, in Elements Values or backend names, in Variables, on Elements hide/show conditions and in Actions, in Custom JS, basically anywhere where the platform need to work on any kind of text field.
The following notation activates math calculation on any of the elements  =(..... + .....)= , where simple math signs denote the operation needed. Numbers or data come into the same way, as with basic spreadsheets:
=( 5 + 100 )= OR =( 3 * 100 )=
For Functions wrap data source into additional parentecies, just like with Functions in spreadsheets, for example the square root funtion:
=( sqrt(4) )=
You can include Hashtags references to perform calculations with any data from any part of platform and build math expressions with it. For example:
=( #hashtag1# + #hashtag2# )= OR =( 3 + #hashtag2# )=
In the example below you can see that the Text field with the Formula has the =(........)= notation to sum of two data sources incoming from two inputs. So when user changes the input, the resulting calculation is also updated.
The rest can be found here  https://mathjs.org/docs/index.html
Action  Example 
SUM / Multiply  =( #hashtag1# + #hashtag2# )= / =( 5 * 2 )= 
Subtract / Divide  =( #hashtag1#  #hashtag2# )= / =( 6 / 2 )= 
Modulus  =( #hashtag1# % #hashtag2# )= 
Exponentiation  =( #hashtag1#  #hashtag2# )= ^ =( #hashtag1# / #hashtag2# )= 
Square root  =( sqrt(#hashtag1#) )= 
Factorial  =( #hashtag1#! )= 
You can also check the set up of some of the above functions on screen  4 Math expressions & operations in Demo App in your profile.
