Changing Miller-family integers changes the checked reciprocal spacing. Exact arithmetic here means exact results for the stated model inputs; measured inputs still carry uncertainty and significant-figure limits.
highlighted = computed this step
The one-zero-zero family leaves six metres between planes
Cell side 6 metres and index family 1, 0, 0 gives square sum 1 and spacing 6 metres.
d=6/1=6
The two-one-two family compresses spacing to two metres
Keeping cell side 6 but using family 2, 1, 2 gives square sum 9 and spacing 2 metres.
d=6/9=2
The four-zero-three family makes a six-fifths spacing
The family 4, 0, 3 gives square sum 25 and spacing 6/5 metres.