There are various ways in which calculators interpret keystrokes. These can be categorized into two main types:On a single-step or immediate-execution calculator, the user presses a key for each operation, calculating all the intermediate results, before the final value is shown.On an expression or formula calculator, one types in an expression and then presses a key, such as "=" or "Enter", to evaluate the expression. There are various systems for typing in an expression, as described below.
... differential calculus textbook, and later used it with Machin-like formulae, including 4 = 5 arctan 1 7 + 2 arctan 3 79 , {\textstyle {\tfrac {\pi...
The pinwheel calculator is a type of mechanical calculator that uses a series of rotatable pinwheels—discs fitted with spring-loaded pins that can be extended to represent digits...

Such details provide a deeper understanding and appreciation for Calculator Pi.
Greg Beech says here that he asks C candidates to produce a formula that calculatesPIGiven thatPican be estimated using the function \$4 * (1 ...
I just finished writing a neat little application that lets you calculatepito lots and lots of digits. ...pipre-calculated to millions of places, ...

As we can see from the illustration, Calculator Pi has many fascinating aspects to explore.
Video · CalculatingPiwith Skittles and Census Data – Numberphile ... Feeling Grumpy aboutPiDay – Numberphile
To get started, we've created a codelab where you can create and calculatepion a Compute Engine virtual machine with step-by-step instructions.