I’ve often tried to use MS Word tables and do computations with the values in the tables. Example:

Suppose, the following conditions hold true:
c1 = a1xb1
c2 = a2xb2
a3 = a1 + a2
b3 = b1 + b2
c3 = c2 + c2

Click on the c1 cell, click on the “Layout” button, click on “Formula” button, in the Formula field, enter the following:
=PRODUCT(a1:b1)
Similarly, for c2 use =PRODUCT(a2:b2).
For a3,b3,c3 use =SUM(ABOVE)

Using watermarks in word documents looks really cool. But the problem occurs when the documents become too big. In such cases, the document becomes exceedingly slow to react to scrolling. Adobe PDF conversion is an even bigger problem.
To remove the watermark it is simple enough : Format -> Background -> Printed Watermark. Then click on “No watermark” and you are golden (or you should be golden).
I’ve observed that the watermark does not get removed many times when you have too many sections in the document.
In such cases: Goto View -> Header and Footer. Click on “Show/Hide Document Text”.
You should see that all your text has disappeared except the watermark. Click on the watermark and you should be able to select it like a floating image. Press the “delete” key and lo! behold! the watermark is gone.
This took me a while to figure out and it was quite frustrating. I hope this post helps someone!