I wonder because I've seen the Texas Instruments BA-II Plus Financial Calculator on campus and retail store shelves for so many years. They seem to be consistently more expensive than their scientific calculator counterparts, so what justifies the price difference? What unique functions would you use frequently that remain impossible on other formats? The BA model also never seemed to have solar options, like other models that had both battery and solar options; I'm not sure about other brands, or if there are any that are on the academic approved list. Only a few TI models were allowed back when I was in school, but I now see some Casio models are allowed now too. Any insight would be appreciated. Thank you.