Have you ever used a text object to test your calculations?
I know I do it all the time. After a while I end up with these cryptic text object without any obvious meaning.
To make it more apparent an option is to add text to show the intention.
Often I find it more convenient to use a Pivot Table, with the expression I want to look at or play around with.
Now it is very easy to add, change and apply expressions and observe the results in a nice and tidy table form.
The only thing to keep in mind is that the chart in this shape does not have any dimensions, so all expressions will be processed as expression totals just like a text object.