HP 49G Graphing Calculator, 1999
The HP 49G graphing calculator was developed for advanced math, science and engineering high school and college students. Users could choose between algebraic notation or Reverse Polish Notation (RPN) for entering equations (RPN is a system for representing mathematical expressions without the use of parentheses). Step-by-step solve allowed students to see the process of obtaining the correct answer. The HP 49G created an environment where students could fully integrate graphic, numeric and step-by-step symbolic manipulations.
With 1.75MB of memory (three times the memory of other calculators on the market at the time), it cost $180 when it was introduced.
The HP 49G had a step-by-step solve feature so students could see how to arrive at the correct answer.