Example 1 (length): A wrench is 10 in long. Provided factor: 1 in = 2.54 cm. Each inch CONTRIBUTES 2.54 cm, so centimetres = 10 x 2.54 = 25.4 cm. Compare T3U01's direction: going cm -> in we divided (counting groups); going in -> cm we multiply (building the total). The factor sentence decides: '1 inch IS 2.54 centimetres' - scaling up the count of inches scales the centimetres with it. Example 2 (speed/distance): A US speed limit sign reads 60 mph. In kilometres per hour: 60 x 1.6093 = 96.558 -> ≈ 96.6 km/h - which is why a Canadian driver glancing at a US sign should think 'a bit over one-and-a-half times.' Example 3 (temperature, reverse formula): Convert 77°F to Celsius with the provided °C = (5/9) x (°F - 32): subtract first - 77 - 32 = 45 - then (5/9) x 45 = 25°C. The brackets exist because the shift must come off BEFORE the rescaling; T3U01's forward trip (25°C -> 77°F) proves the round trip works.

Convert 8 in to centimetres (1 in = 2.54 cm) -> 8 x 2.54 = 20.32 cm