"Here is an interesting site about US Cents, commonly called "Pennies".

The site is non-numismatic (which you can tell from the get-go by the use of the term "penny"), but it uses cents to illustrate large numbers through one quintillion. One (fractured) numismatic tidbit is: "Current estimates by the U.S. Mint place the number of pennies in circulation at around 140 billion. Others have estimated as many as 200 billion currently circulating. Since the first penny was minted in 1787, until present-day, over 300 billion pennies have been minted in the United States. So that leaves about 100 billion pennies that have been retired by the Mint, lost down sewer drains, stored in jars, smashed by trains, or collected by numismatists in the past 200 years." http://www.kokogiak.com/megapenny/