A High-Interest Calculation Using Exponential Notation

applications - anJ analogies Your Share of the National Debt A High-Interest Calculation Using Exponential Notation William Hoyt Saint Joseph's College Windham, ME 04062

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'lass, begin with a math reIn my general view, which includes operations with exponential numbers, Using (rounded-off) values of four trillion dollars ($4,000,000,000,000) for t h e debt and 250 million 175n ~ - - - , - nnn - - , - - -no0 , - - - ,nnn) r . . r .npnnlp . . . . . . . . in the United - - - - - - - States. the & d e n t divides 4 x 10" dollars by 2.5 x 10' people to find that the

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RONDELORENZO Middle Georgia College Cachan. GA31014

per capita share is 1.6 x lo4 dollars, or $16,000, the cost of a new ear. This is their indiuidual share of the debt. I then comment that our class (about 30 people) owes almost half a million dollars. A further instructive calculation is the per capita interest on "their" share of the debt. Assuming 5%, the students find that $1.6 x lo4 x 5 x lo-'% = $800, the cost to finance their small art of the debt: the first $800 of their taxes go only to service the debt already incurred by past Congresses. This always has an impact on the class. This calculation is not only an exercise in exponential number manipulation; but also it shows students the size of the debt in terms that they can relate to, and it really holds their attention

Volume 72 Number 9 Seotember 1995

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