Quick matematics  
Can you imagine how useful it would be to have a dialogue box that would allow you to perform on the spot calculations?
In other words, to be able to perform calculations using the values of certain cells within a dialogue box. This way you would not have to waste time performing calculations in the worksheet and then have to erase them.
To achieve this, follow my instructions:
After you click on the respective button in the tools bar, the following dialogue box will appear:
In the space labeled Math action, we must enter the symbol representing the arithmetical calculation we are planning on doing; then we enter the value we wish to use.
Something like this:
Then, we start scrolling through the cells we are interested in. Note that the results of the calculations will be displayed in the area labeled Results.

If we add + 5 to the value of the active cell, we would have 55.45. That is what the tool does: it performs quick calculations.

Let us go on. Notice that the dialogue box has a button labeled Enlarge. Click on it, and the dialogue box will change its size.

If you "check" the space marked with red, several mathematical options will be activated. They will allow you to work with cell ranges.
See the figure below.

What has happened here is as follows:
1.- The selected range was added; and then, + 5 was added to that sum. The total would be 197.48.

Think of the great things you could do with this tool.