I was wondering about the size of the scientific calculator market, and the shares of hp, ti, Casio... is there any reference on that? The only datapoint I have is Casio celebrating the 1 billion mark a few years ago (all calculator types included).

I found a Wall Street Journal article from 2009 that was about the TI N-spire that lists market share for the U.S. concerning graphing calculators. The article uses NPD (national purchase diary) as the data source. The article states that TI has 80% and HP 5% but doesn't give a percentage for Casio. However it says Casio is second in market share so i infer that means 15%. I'm sure that there are forum members that will be able to shed more light on the subject.