A cobweb diagram is source-bound geometry, not a free sketch. Exact arithmetic here means exact results for the stated model inputs; measured inputs still carry uncertainty and significant-figure limits.
highlighted = computed this step
Cobweb points come from the ledger
The plotted states are the seed, one quarter, three eighths, and seven sixteenths.
0,41,83,167
The step segments are checked geometry
There are 4 source points and 6 checked cobweb segments.