To calculate the present value (PV) using the formula PV = PMT * (1 - (1 + i)^-n) / i, the example provided shows PV = 225 * (1 - (1 + 0.0055)^-42) / 0.005, resulting in PV = 8417.37. Users are seeking guidance on how to input negative exponents on a scientific calculator, specifically the Texas Instruments TI-30x IIS. The discussion highlights the importance of identifying the correct buttons, such as the Change Sign button, which may be labeled as (-). For further assistance, users are encouraged to consult the calculator's manual for detailed instructions. Understanding how to properly use negative exponents is crucial for accurate calculations in financial formulas.