Another worked example

Here's how I'd do an exercise. Particularly useful for preparing for exams.

Here's the exercise.

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Cthuhlu plans to knit leg warmers for his goat friends. Write a program to work out how much yarn it will need. Yarn is measured in geins. Like a skein, but for goats.

There are three sizes of warmers: small, medium, and large. Here are the number of geins.

Of course, each goat will need four leg warmers.

Here's what the worksheet should look like to start:

Here's some output:

And some more:

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STOP! Before watching the video, try the exercise yourself.

You tried it?

You did, right?

OK, here's how I'd do it.