Find the volume of a cylinder with a radius of 3" and a height of 12"

Here's the formula you need to use:

The volume of any cylinder is = (pi) x (radius) ² x (height).

Take that formula.

Write your "3 inches" in place of "radius".

Write your "12 inches" in place of "height".

Write "3.14" in place of "pi".

Do the arithmetic, and bada-bing, you'll have the volume.