If you use MindManager to track and collate sales data or other financial information you can use the Topics2 Total addin to quick calculate the total of multiple selected Topics providing that the Topics contain purely numerical Text.

With the Topics selected click the Topics2 Total menu button

A dialog will appear that shows the calculated total and gives you the option add a Topic to the Map

If you select the option to Display the result as a new Floating Topic in Map then you get the following result

You can now drag this Topic to a new location and edit the text to suit your subject.