I tried to do it on the bubble, but nothing comes out.
Those. the first multiplication goes well, and the second is no longer working, the result shows 0. Although it is possible to subtract from the resulting number, add.
What to do? Where is the mistake? Here is a page where the explanation and attempt to make

I don’t have any examples with complex operations in my apps. But I do have an invoicing system. To give you an idea, here’s how I do simple calculations for a ‘charge’. You’ll of course, reference your own data points and enter the type of calculation you’re looking to achieve.

Glad to hear! Bubble has built in functionality of doing simple calculations. Here I have just a simple input set as an integer, and a text field to display the outcome. So, you could have multiple fields, and set the text field as ‘Input A’s value * Input B’s value / Input C’s value’ etc etc etc.

Yes, simple and one-time mathematical operations can be done. But, for example, you will not be able to multiply the result of the past multiplication.
That is, Input1 * Input2 you can do - you get value1. But you can’t multiply value1 by input3