It turns out, $600 billion is a very popular number and often makes news.  Let's find out why.

$600 billion is the: 

1. Approximate cost to put a human on Mars.
2. Approximate proceeds from the worldwide sale of illegal drugs per year.
3. Widely believed cost of the "Y2K bug" to the world economy.
4. Approximate annual sales of all counterfeit products worldwide.
5. Approximate cost of the Vietnam war in 2007 dollars.
6. Approximate amount the U.S. stock market shrunk during 2006.
7. Approximate value of the trade surpluses of oil-producing nations thanks to rising oil prices.
8. Approximate amount Americans spend on legal gambling.
9. Approximate size of the U.S. travel industry.
10. Approximate cost of the War on Terror for U.S. citizens.