It is easy to insert and use formulas. There are only a handful of formulas you can use but its enough to get totals counts round numbers etc. See How to reference a cell of a Word table for more details.
You can create formulas in Word to perform simple arithmetic calculations such as addition subtraction multiplication or division.
Also if you are already familiar with Excel then using the formulas in Word will be a piece of cake. Microsoft Word allows you to use mathematical formula in table cells which can be used to add numbers to find the average of numbers or find the largest or the smallest number in table cells you specify. The Formula popup in Word 16 Under Formula Word takes a guess as to the formula you might want to use and displays SUM LEFT. Form fields can store static values and formulas.