In the financial formulas described in Chapter 10, “More Excel financial functions,” I used a last argument of 1 to indicate end-of-month cash flows and 0 to indicate beginning-of-month cash flows. Excel recognizes True as equivalent to 1 and False as equivalent to 0. Set up a worksheet in which a user can enter the number of months in a loan, principal, and annual interest rate to find the monthly payment. Then use a check box to select whether the payments are at the beginning or the end of the month.