Various economic theories differ about the relationships between key economic processes of production, distribution and consumption of things, whether goods or services, and about the management of those processes. But each theory seeks mathematical support for its assertions. David Ricardo used mathematics to demonstrate comparative advantage. Karl Marx used mathematics to demonstrate surplus value. John Maynard Keynes used mathematics to demonstrate aggregate demand. Ludwig Von Mises used mathematics to explain his theory of money and credit.
Modern economics revolves around money. Money is a medium for introducing a like-quantity between two or more things that have unlike qualities. A book is not a shrimp dinner, but each has a monetary value that may be the same. Each is exchangeable for money, whose quantity is the only thing that changes. Money doesn't become some quality other than money. Money only differs in its quantity. Determining exchange values using money is, therefore, an inescapably mathematical process.
Wages are determined by multiplying a constant, the wage, by the number of hours worked. Interest is determined by multiplying an annual rate by a principle, and multiplying the product of the last calculation by the length, in years, of the loan. Gross Domestic Product is determined by counting the amount of money that changes hands in a given territory over a period of a year. Whether you are stating profits and losses, preparing a payroll, balancing a checkbook or running a government accounting office, a great deal of what you do is mathematical calculation.
Economist Kenneth Boulding once said, "Anyone who believes exponential growth can go on forever in a finite world is either a madman or an economist." His critique was of economists who only counted growth without factoring in the environment. While this critique did not use a mathematical calculation, he still used two fundamental mathematical concepts: finity and infinity. This is one more demonstration of how economics is inescapably mathematical. Boulding gets the last word, then, in his most explicit statement of the relation between mathematics and economics: "Mathematics brought rigor to economics. Unfortunately, it also brought mortis."