may be additional positive or negative answers, or no true solution at all. You can continue searching for other solutions by halting the calculation and entering a different guess.

One way to obtain a good guess for IRR% is to calculate NPV for various interest rates (I%). Since IRR% is the interest rate at which NPV equals zero, the best estimate of IRR% is the interest rate that yields the value for NPV closest to zero.

To find a good estimate for IRR%, key in a guess for IRR% and press Then, press to calculate NPV for that value. Repeat the calculation of NPV for several values of I%, and look for trends in the results. Choose as your guess for IRR% a value of I% that produces an NPV close to zero.

Solver Calculations

As noted in chapter12, the Solver uses two methods to find solutions, depending on the complexity of the equation: direct and iterative (an indirect). To use all the calculating power included in the Solver, it would help to understand, in a general way, how it works.

Direct Solutions

When you start a calculation (by pressing a menu key), the Solver first tries to find a direct solution by “isolating” the variable you are solving for (the unknown). Isolating a variable involves rearranging the equation so that the unknown variable is by itself on the left-hand side of the equation. For example, suppose you enter the equation:

P R O F I T = P R I C E C O S T

If you’ve stored values for PROFIT and PRICE, pressing causes the Solver to internally rearrange the equation algebraically to solve for COST (COST is the unknown):

C O S T = P R I C E P R O F I T

Answers calculated this way are called direct solutions.

240 B: More About Calculations

File name : English-M02-1-040308(Print).doc Print data : 2004/3/9

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HP 17bII manual Solver Calculations, Direct Solutions, O F I T = P R I C E - C O S T, S T = P R I C E - P R O F I T