Why do I have the word "squared" in the image captions? Because the penny, nickel-and-quarter, and dime-and-loonie coins are related by the "squaring" operation. 1-squared is 1; 5-squared is 25; and 10-squared is 100.
On a sad note, neither of the above images survived the editor's digital scissors. Happily, the following really useful image did sneak in during editing.
As always, my DeHaan Services blog has an entry to publicize my article. "The Infinite Set Paradox of Galileo" adds little to this discussion, but is important for those who find my articles through that front-end.
For example: why do the first two images use the word "square"?