This too is born as a preview, so I have a copyright record of the images I made for the article to be published at Decoded Science.
I've also publicized this article, with additional Canadian content, in "What is Compound Interest at Decoded Science" at DeHaan Services.
One Writing Tip with Interest
It might have been possible to write one article about calculating interest.
However, it would have been longer than the Decoded Science ideal length.
It would also lose focus, especially for anyone looking for a really specific answer to either simple interest or compound interest.
There's no harm in writing a series of articles, unless you deliberately chop up one useful concept to increase the number of page views.
Conversely, readers who have to scroll through too many virtual pages, or click "next" seeking the elusive kernal of wisdom, are likely to give up in despair.
So the writing tip is to focus your article on one topic; cover it well; and write a series to cover the material that overflows the one-article-sized container.