A detector cell grid turns spatial coverage into a finite ledger: cell count times pitch gives the covered length. The arithmetic is exact only for the stated cell pitch and count; real detector coverage also depends on alignment tolerances, edge gaps, fabrication variation, and calibration uncertainty.
A finite cell grid covers count times pitch. Exact arithmetic here means exact results for the stated model inputs; measured inputs still carry uncertainty and significant-figure limits.
highlighted = computed this step
Cell count times pitch gives coverage
The training detector has 4 cells, each 2 meters wide.