We ordered ‘Mellow Mushroom‘ pizzas for supper last night and we still have about one pie left over in the frig, just waiting to be finished off.

Now: What is pizza? one way to say it is to assume the thickness of the pie is the value $'a'$ and the radius of the pie is the value $'z'$ then to say, “What is Pizza?” could be to ask, “What is the volume of a pizza?”

Thinking of a pizza as a very thin cylinder of height $'h'$ and radius $'r'$ we get.

[1] $V = \pi r^{2}h$

Substituting $'a'$ for the height $'h'$ and $'z'$ for the radius $'r'$ we get:

[2] $V = \pi z^{2}a$

Next  recall that the greek letter $\pi$ can be written in English as $Pi$ we get:

[3] $V = Pi z^{2}a$

Finally expanding the $z{2}$ to be $z z$ we get:

[4] $V = Pi z z a$