QUICK LOAN CALC. RETURNS RATE

Given 3 of the 4 parts of a loan...namely, PRINCIPAL, INTEREST RATE, TERM (in months), and lastly, PAYMENT this app will calculate the 4th empty data field using values from the supplied other 3 fields. Once it calculates the 4th field's result it then calculates FUTURE VALUE AS AN INVESTMENT and REALIZED FUTURE VALUE GAIN. It's rare to find an app that returns INTEREST RATE (I couldn't find such an app) using PRINCIPAL, TERM and PAYMENT as input. This app uses binary halving to bump the rate until it produces the supplied PAYMENT or the difference between the calculated PAYMENT and the supplied PAYMENT is less than .004.