system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Do I get more pizza with one 18" or two 9" pizzas? Is there a formula I can use to work out the relationship between the areas of different sized circles?
gpt
Pull out two coins and set them side by side.

See how the two together are wider then they are tall?

Imagine a circle around the whole thing that touches the left and right sides.

See how much higher then the coins that circle goes?

The same thing works for any circle, including pizza, see all that missing space between the actual coins and the imaginary circle? that's all the pizza you can't have if you get the two small ones!