Introducing pupils to algorithm design and coding in general is not always straight-forward but Flowgorithm is a big help. We will try to play Archimedes and use modern science to find out costs of various cylinders, such as coins and sports medals. It can be linked to this article on the true cost of Olympic medals. Here is an example of a lesson or homework resources that introduces a number of operators, including "to the power of", rounding, etc with a multipart assignment with built-in AFL. Both the PowerPoint version and the PDF versions are included, as well as the solution, of course. Flowgorithm file is here.
You might want to scaffold the solutions by asking pupils to think through by listing which variables are needed, any constants, which operators, and in which order. The solution provided can be printed larger, cut up into shapes and given to pupils to arrange for extra scaffolding.
Pseudocode and Python code are included on the left margins for additional testing.