Calculations - JavaScript

[Andy Bills]

Hello,
I am hoping someone could perhaps help me or give me some guidance please.

What I would like to do:

I have a series of number entered into one field, the numbers are separated by a comma, what I want to do is add these up and display in another field, for example;

3.45, 5.65, 8.95

Total displayed in another field = 18.05

The numbers do not have to be separated by a comma, I could write 3.45+5.65+8.95

The numbers in the string could vary, typically 3 or 4 but up to 10.

I am aware that I could add the number in to separate fields but this could be difficult to follow as this will be used in a fillable form on a mobile device and was wondering if this could perhaps be achieved using javaScript.

I really appreciate any help, thank you