Of the business/finance calculators out there today, I feel the BA II Plus is the has the best value.  It has it all:  TMV (Time-Value-of-Money), Random Numbers, Percent Changes, Depreciation INCLUDING declining balance with crossover to straight line (very useful for taxes), profit analysis, and bonds (just to name a few features of this wonder).  I first bought this calculator in 1990 and enjoyed its use ever since.  I just purchased the "new" BA II Plus, with sturdier keys.