Ethan can count up to around fifty, but beyond that ends up cycling backwards at one of the decade boundaries. The largest number he knows is one hundred. The concept of numbers beyond makes some sense to him, but is quite abstract.
Here’s an example: Ethan asked me to watch him as he rode his tricycle over the garden hose. The act itself wasn’t what interested him; it was just an object lesson for what followed: “A wheel loader would break the hose. It's a hundred heavy.”