A calibration line can compute an inverse value while the range gate still matters. 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 first unknown satisfies the calibrated line
The standards give slope 3 and offset 2. Signal 5 calibrates to value 1.
5=2+3⋅1
A higher in-range signal maps to a higher value
Signal 11 uses the same line and maps to value 3. The row remains inside the declared standards.
11=2+3⋅3
Out-of-range signals are visible even when arithmetic closes
Signal 17 would calculate to value 5, but the signal is beyond high standard 14.