It was the default for professional engineers and accountants. TI made calculators for school children, so added an algebraic interface, removed anything not al

It was the default for professional engineers and accountants. TI made calculators for school children, so added an algebraic interface, removed anything not allowed by the College Board exams, and simplified and standardized. Great educational tool. Terrible professional tool. That said, I learned a lot using an HP in high school and porting over all the TI programs provided by the teacher.