I found two documents that I was very proud of as a child. Both were the result of trying to understand the kind of things Ramanujan did in free time, a result of the little AMTI books I read as a child. I will share one document in this post and another one in the next since both are not related to each other in substance.
Following is a calculation table generated using some spreadsheet software:
As you can see, it was motivated by the famous Taxicab number story.