Forget about that. Instead focus on liabilities as presented in Revised Greek Default Scenario: Liabilities Shifted to German and French Taxpayers; Bluff of the Day Revisited.

The above total is a "modest" €256 billion to be paid back over time.

 Assume 0% interest

Assume a Current Account Surplus of 3% of GDP

Assume Greek Debt-to-GDP is 176%

Assume Greek Debt €312 billion

Assume Greek GDP is €178 billion

Point 5 is derived from points 3 and 4. The numbers seem to vary a bit depending on the source, but they should be close enough for this exercise.

Payback Math at 0% Interest

Let's assume that Greece can run a 3% current account surplus for as long as it takes to pay back €256 billion.

3% of €178 billion is €5.35 billion. To pay back €256 billion it would take about 48 years. That assumes 0% interest and a 3% current account surplus every year for 48 years!