Memory trick: How many 'X' in an 'X'?

This clever diagram illustrates the "gallon-eating-the-quarts" trick.

So there are:

2 Cups in a Pint
2 Pints in a Quart
4 Quarts in a Gallon

And so two "C's" fit inside a "P," two "P's" fit inside a "Q," and four "Q's" fit inside a big, enormous "G."

It's like "the woman who swallowed a fly" for cups and quarts!

It still takes a few minutes of mental visualization, but with this diagram in mind, you can easily figure out that there are four cups in a quart, 16 cups in a gallon, and so on.

This clever one comes from here:

Now if I can only find this for the European measuring system in liters!