Tuesday, September 23, 2008

How Many Pennies?

Moving from Chicago to Texas has left us strapped for cash.  We're so poor that I'm going to cash in the jug of pennies that's been a doorstop in my childhood bedroom for about twenty years.

How much do you think is in there?  

According to this site, the volume of a penny is right around .35 cubic centimeters.  Precision in this matter is difficult.  Before 1982, pennies were a little bigger than .35, and later pennies are smaller than .35.  We'll call it .35.

Using google's handy conversion feature, I see that 1 U.S. gallon is 3,785.41178 cc's.

Without air voids and assuming it is filled to the gallon line, there would be room for 10,815 pennies in this jug.  As we can see, though, pennies are not a shape that can be stacked or crammed in such a way as to fill a space completely.  So how much air is in there with the pennies?

We could be rigorous about this guess, maybe by seeing how much water the jug will accept in addition to the pennies.  But I don't really want to pour wet pennies into the counting machine tomorrow.  Instead, I'll make a wild guess.  In our tradition of making oddly precise guesses, I say that 87% of the volume is coin and 13% is air.  Sally guessed 92/8.  Splitting the difference at 89.5%, then we should have $96.79 in the jug.

Give us your best guess in the comments section.  We'll post the results as soon as we cash in.  The person with the closest guess will receive nothing and like it.


Pre-1982 pennies are 95% copper, and the first ten pennies I pulled off the top of the jug are pre-1982.  Although you could get more than a penny by salvaging the copper in each penny, it's actually illegal.  Don't even think about it.

Update 2:

Kat was very close.  We cashed in 5548 pennies this evening.  That means the space in the jug was 48.7% air.  


Matt said...

Now that I'm really looking at this thing, I'm thinking our initial guesses were way too high. We'll see.

America said...

Oooo, I get to be the first one since I cannot sleep! Ok, so I am allying myself with Sally or maybe Matt, whoever is right, my guess is $88.88!

katherine petillo said...


Jacki G. said...

Okay, looking at the change that my mom and brother recently cashed, I'm thinking that maybe about 7,000 pennies, and about 70 dollars. Gimme a hollar and tell me what it actually was!

katherine petillo said...

I must admit that we recently cashed in a penny jar. I assumed it was about the same size. Ours had $54 in it, but a few nickels, dimes and quarters had slipped in over the years.

America said...

Ok, so she cheated then ;) I win by default and totally not putting any brain power into it.

katherine petillo said...

cheated? how is that cheating?