**Update:** *Stephen Downes quite rightly takes me to task for the strike-throughs in the original essay, preserved here to keep me humble. I tracked down my error after he got in my face (in comments below). *

*When I used Wolfram|Alpha to convert pounds of silver to dollars, the website converted the sum of pounds of silver to Pounds Sterling… and I realized I needed to convert 2,320,000 pounds of silver to kilograms. Then I multiplied 2,320,000 by 2.2 instead of dividing… 5,104,000 kg of silver instead of the right number. Then I forgot basic metrics, and substituted kilo- for cento- …. Ack. See this yellow-clear stuff on my nose? See that? ***That’s egg. On my face.**

For the last several days, I’ve been wondering about Arrian’s assertion in his life of Alexander the Great, that at the capture of Persepolis, Alexander and his army captured 40,000 talents of silver.

Now, a talent is a measure from ancient times, about 58 pounds of silver or gold. So I’ve been wondering, how much is that?

I’ve asked a few colleagues, and it turns out that people are curious. Not as curious as I am perhaps, but curious. But it’s been gnawing at my insides for a few days, and I didn’t know how to solve the problem.

Then I realized, I DID know. I used Wolfram|Alpha. So, 40,000 talents of silver is about 2,320,000 pounds. And that amount of silver is 96.4 cubic meters – not quite a cubic kilometer of silver, but close.

And its current street value? Around 2.6 billion dollars. $545 million.

So maybe Arrian is exaggerating. It’s possible. It’s even likely. Maybe it’s not pure silver.

But say that he isn’t?

It kind of explains why the economy of the Middle East took off, once Alexander died and his generals finished settling who got what. A lot of soldiers had a lot of money in their hands, and were looking to spend. Money that had been sitting in a royal treasury slipped out into the rest of the economy. And that paid for things like the Colossus of Rhodes and the Library of Alexandria and the troops that caused such difficulty to the Maccabees and… and…

It paid for Hellenism.

In the current climate of on-again, off-again confrontation with Iran, it’s probably worth keeping in mind that the sack of their ancient capital, and the looting of their empire, helped jump-start the scientific revolution that led to the rise of the West.

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[…] DON’T want anyone to walk away from this thinking that I know how to teach math (I don’t, and I shouldn’t), or that I think that my colleagues who teach math are dumb or wrong-headed. I think […]

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[…] 26, 2010 · Leave a Comment Stephen Downes tells me I shouldn’t teach math. (I did preserve his comment, by the way, on my 40,000 talents post, though I did edit the entry. No point in leaving wrong […]

Um… don’t teach math.

You shouldn’t need to look up 40,000 times 58. Because 4 x 6 is 24, 4 x 2 = 8, you know the amount is 2,400,000 – 80,000 = 2,320,000. No calculator needed.

You might not know that your silver is a bit more than 10 grams per cubic centimeter (CC) http://en.wikipedia.org/wiki/Silver , so you may have to look up the fact that just under a million kilograms of silver (1 kg = 2.5 pounds, roughly) is just under 100 cubic meters.

But there is no excuse for saying that 96.4 cubic meters is close to a cubic kilometer. First of all, a kilometer is 1,000 meters, not 100. Second, a cubic kilometer = 1000 meters x 1000 meters x 1000 meters = 1,000,000,000 cubic meters. One billion cubic meters, not 100 cubic meters.

The value of silver is generally around 15 dollars per ounce (today it’s about $16.50 – http://silverprice.org/silver-price-history.html ) and there are 12 avoirdupois ounces to a pound, so a pound of silver is worth $180. Say, about $200 today.

200 x 2 million = 400 million, so there’s no way $200 x 2,320,000 is $2.6 billion. More like $464 million. Silver would have to be priced at $60 per ounce to be worth that much. Silver peaked at about $50 an ounce once in 1980, but has otherwise never been close.

To put things in perspective, if I had a 1 gram dime to sell, your calculations would result in it being 1 million grams, which you would buy from me for $12,000.

And now you have a very clear sense, Stephen, of why I got a nearly-perfect score on the verbal section of the SAT, and later on the verbal and analytical sections of the GRE; and why I nearly blew the mathematics sections. 🙂

I make these sorts of errors all the time. Sometimes they’re costly errors, and sometimes they’re minor, but if it comes to math, I frequently blow it. This is why I stick to literature, history, and occasionally Latin. As you suggest, so shall I do.

I’ll edit this piece to conform with your commentary.