A below-gap photon does not cross the toy threshold. 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 lower frequency gives a lower energy ledger
Frequency 2 hertz with the same h gives photon energy 4 joules.
E=2⋅2=4J
Below the gap means rejected in the toy threshold
The gap is 6 joules, so a 4 joule photon has accepted bit 0.