Why do even the simplest calculators feature a square root key?

[hibiki]

Dieter, aside the marketing aspects explained above, I think I found another clue for square root function present in simple calculators.
I made a research in the book "Inside Your Calculators - Gerald R. Rising - Wiley 2007". This books presents the algorithms used in calculators.
In synthesis, once you have implemented the four arithmetic basic operations and have some free registers memories, to implement the square root function is very easy using Newton´s Method (sucessive aproximation) that is a short routine and fast to find the root. The implementation of Integer Power is easy too, but Rational powers is not so easy to implement. The algorithm described in the book for rational powers uses the square root function, and is a bit longer routine. So in my understanding based on this book, the square root function precedes the power function, and is not dependent of nothing more than the basic operations division, addition and compare.