If you need to figure out some arithmetic calculations, you don't want to bring up your computer's native calculator. You can easily add a calculator into MS Word.
>> Go to
File -->
Options -->
Quick Access Toolbar -->
All Commands (Choose commands from:)
>> Select
Calculate Command and
Add to the Customized Quick Access Toolbar -->
OK>> Now you can find a non-descript
gray circle at the top of your Word window(on Quick Access Toolbar)
>>
Highlight an equation in the document and click that circle, you will find an
answer to your calculation at the bottom of your window(
Status bar)
ref.