Hi - looking to be able to quickly perform functions such as solving for the monthly payment arising from a given loan period, selling price, interest rate and term. Likewise, one that can tell me how much house a buyer can afford if he or she already knows what payment they can make monthly (in other words, solving for that instead of "payment" using the above inputs).

Also one that performs margin calcs - such as how much the seller needs to get in order to acheive a certain ROI on the original investment, etc.

I had one of these years ago but the ones by TI and HP now seem very complicated. Looking to purchase one soon so if anyone who has something suitable for a realtor - not geared toward somebody trying to operate a hedge fund please let me know! Thanks.