The HP-15C is a high-end scientific programmable with a root-solver and numerical integration. It is able to handle complex numbers and matrix operations. Although out of production, its popularity has led to high prices of US$200–400 on the used market and a petition asking HP to restart production. The HP-15C was a replacement for the (LED Display based) HP-34C. On September 1, 2011, HP announced that a limited edition 15C based on the ARM hardware used in the modern 12C would be released.
Read more about this topic: HP-10C Series