There's no feature to "show" you the back end calculations. The most effective way to test your pricing formulas, is to break them down individually by only adding them in to the product one at a time, and testing it (by creating a "pretend" order) to ensure that particular formula performs as it should.
If you have a fully built formula that isn't giving you the value you're expecting then I have some advice on how I would troubleshoot it:
First make sure you don't have any discounts applying to the order in question that might be the cause of confusion.
Then go re-save the pricing tab of your product to make sure you don't have any errors in your formulas (e.g. missing parentheses causing it not to evaluate or missing/wrong variables), and if you're using any variables from your parts then I'd also go re-save the parts tab to make sure none of those formulas have errors.
Next, I would make sure all the variables being used are spitting out a real number (that is also correct). I'm mostly talking about when your variables are coming from select-type/drop down attributes. If you forget to put a value in one of the cells and then that cell gets used in one of your formulas it will not be able to calculate!
