An energy packet stores a fixed amount of available energy that the cycle can draw on, without specifying the chemical reaction path that releases it. The checked value is 12 J per packet exactly for the stated toy source ledger; real molecular motors involve stochastic chemistry, thermal noise, losses, state timing, and measurement uncertainty.
A motor ledger starts with a checked energy packet, not chemistry. Exact arithmetic here means exact results for the stated model inputs; measured inputs still carry uncertainty and significant-figure limits.
highlighted = computed this step
A packet is only an energy source
One packet carries 12 joules in this checked training ledger.
12J
The packet does not describe chemistry
The diagram says energy available, not a reaction path; the checked value remains 12 joules.