When I went to university in 1976, everybody got a calculator. There were two models which sold the most: the TI-57 and the HP-25, virtually no other makes were sold at all. They were essentially equivalent, the TI being rather cheaper but faster. The odd HP-67, SR-52 or TI-59 sold as well, although you had to have rich parents, plenty of savings or mortgage parts of your body to the devil to afford one. HPs were considered the BMWs of calculators, the TIs were the Fords :-) I got an HP-25 which I never regretted, the extra money I spent probably gave me a couple of extra years longer life thanks to less stress using it, owing to RPN. /Jonas