WASHINGTON — President Barack Obama has proposed saving more than $4 trillion over the next decade in his "fiscal cliff" talks with Republicans. House Speaker John Boehner has offered a comparable figure, and two years ago an influential bipartisan commission headed by Democrat Erskine Bowles and Republican Alan Simpson suggested $4 trillion as well.

What's so special about that number?

Nothing really, say many economists. The real key is preventing the enormous $16.4 trillion debt the government owes from growing faster than the now $15.8 trillion U.S. economy.