At the time of writing, the US national debt was just over seven trillion dollars, or $7,019,863,348,183.41 at 11 February 2004 at 01:04:25 PM GMT. When the debt needs to be repaid, the process of delivering the money might be just as complicated as applying the requisite fiscal policies.

A banknote is 100 microns thick. A million microns, or a stack of 10,000 $100 banknotes (worth a million dollars), makes up a metre. So think : one million dollars is a metre, and this is assuming the notes are completely flat and not crinkly like how your Monopoly money is.

One hundred $100 notes (worth $10,000) would make up a centimetre high wad. Make it a metre high, and it now consists of 10,000 notes worth a million dollars. Be adventurous and pile it a kilometer high - that's ten million notes worth a billion dollars.

Such big numbers become harder to scale, but you have to still realise that a trillion is still a few powers bigger than a billion. Ultimately, to pay off the national debt you would need a 7,019 kilometre high pile of Benjamins.

A banknote, regardless of denomination, weighs one gram. The counter of the bank that will accept repayment better be capable of supporting the weight of a money bag weighing in excess of seventy thousand metric tonnes. The SS Titanic by comparison, weighed 41,731 metric tonnes. And you can multiply the weight by a hundred if you choose to pay in single dollar bills.

If you thought Uncle Scrooge's money bin was fanciful, it is still peanuts compared to the kind of voluminous vault the receiving bank will need to store it. A banknote's dimensions is 66.2 mm by 155.956 mm, and consists of 103.242872 square centimetres in area. If you laid down what was owed by America in the form of single dollar bills, you would need about 680,000 square kilometres spare. Myanmar would fit nicely.

Or in the tradition of porting money around discretely to a secret rendezvous, you would have to find a toilet stall or underground parking lot which could accomodate a 8.5km x 4km x 2km briefcase, filled up with non-sequential $100 notes.

ref: www.moneyfactory.com/document.cfm/18/106
www.brillig.com/debt_clock