Question: U.S. debt For selected years from 1900 to 2009, the national debt d, in billions of dollars, can be modeled by d = 1.669e0.0829t where t is the number of years past 1900 (Source: Bureau of Public Debt, U.S. Treasury). How long will it be before the debt is predicted to reach $25 trillion (that is, $25,000 billion)? Do you think the Financial Crisis of 2008 and the subsequent federal stimulus bills have affected this model? Explain.