WEBVTT 00:00:00.000 --> 00:00:01.000 Unit consistency before method selection. A 0.15 m input has been incorrectly transcribed as 15 mm. 00:00:01.000 --> 00:00:07.000 MATHEMATICS · define the relationship and the meaning of each symbol before calculating. 00:00:07.000 --> 00:00:14.000 Conversion factor = 1,000 mm per metre. h = 0.15 m. The incorrect transcription is 15 mm; the correct value is 150 mm. 00:00:14.000 --> 00:00:23.000 INPUT · two values in a common unit · read the axis units and the numerical values. 00:00:23.000 --> 00:00:34.000 A 0.15 m input has been incorrectly transcribed as 15 mm. 00:00:34.000 --> 00:00:43.000 150 mm / 15 mm = 10. Correct the input before applying any method-specific coefficient. 00:00:43.000 --> 00:00:52.000 OUTPUT · relative magnitude · read the axis units and the numerical values. 00:00:52.000 --> 00:00:59.000 The wrong value is one tenth of the correct thickness: relative error = −90%. Conversion precedes method-specific calculation. 00:00:59.000 --> 00:01:05.000 CALCULATION · substitute the defined inputs; keep units through each intermediate step. 00:01:05.000 --> 00:01:08.000 Source thickness: 15 cm × 10 = 150 mm mm 00:01:08.000 --> 00:01:11.000 Incorrect entry: 15 mm / 150 mm = 0.1 dimensionless ratio 00:01:11.000 --> 00:01:14.000 Relative error: (15 − 150) / 150 = −0.9 −90% 00:01:14.000 --> 00:01:17.000 Independent stack: 40 + 150 + 200 = 390; wrong stack = 255 mm total thickness 00:01:17.000 --> 00:01:26.400 SENSITIVITY · change one declared input · read the axis units and the numerical values. 00:01:26.400 --> 00:01:29.800 Base 15 mm: 255 mm total stack. Surfacing 40 mm plus base 15 mm plus subbase 200 mm. 00:01:29.800 --> 00:01:33.200 Base 150 mm: 390 mm total stack. Correctly converted base; other layers unchanged. 00:01:33.200 --> 00:01:36.200 Base 165 mm: 405 mm total stack. A separate +10% base-thickness sensitivity case. 00:01:36.200 --> 00:01:42.200 Check: Round-trip source units through the canonical representation and compare against the original value. Validate each layer separately, preserve source units, and withhold a derived-method result when the source equation or applicability remains unresolved. 00:01:42.200 --> 00:01:55.200 ONE ROW · A factor-of-ten error does not announce itself with a red flashing cell. 00:01:55.200 --> 00:02:05.200 PARAMETER MAP · 6060 evaluated cells. The colour limits stay fixed across every row. 00:02:05.200 --> 00:02:15.533 Most rows convert centimetres to millimetres correctly. Every tenth row deliberately leaves the number unchanged. The regular low bands are planted defects in an import test, not a 00:02:15.533 --> 00:02:22.908 material trend. Compare equal reported thicknesses across batches: the unit conversion should be invariant to delivery date or file name. 00:02:22.908 --> 00:02:31.325 INTERPRETATION · These are discrete states. Read the map cell by cell; a smooth surface would invent intermediate categories. 00:02:31.325 --> 00:02:36.742 Unit conversion is computed; pavement-number coefficients are not invented.