That section comes from the part where Milo and his companions arrive in the Number Mines and are completely famished because they’ve been travelling all day. They eat and eat but never get full. Eventually, the Dodecahedron helpfully tells them that they’ve been eating Subtraction Stew because it’s perfectly logical that you’d start off full and eat until you’re hungry.
I’m remembering a passage in Childcraft about eating soup made of negative numbers that made you hungrier.
That section comes from the part where Milo and his companions arrive in the Number Mines and are completely famished because they’ve been travelling all day. They eat and eat but never get full. Eventually, the Dodecahedron helpfully tells them that they’ve been eating Subtraction Stew because it’s perfectly logical that you’d start off full and eat until you’re hungry.