To convert temperatures from Rankine to Celsius, subtract 491.67 from the Rankine value and then multiply the result by 5/9. This formula reflects the relationship between these two temperature scales, where the Rankine scale is an absolute scale based on Fahrenheit degrees, and the Celsius scale is based on the metric system. For example, to convert 600°R to Celsius: (600 - 491.67) × 5/9 ≈ 60.18°C. This conversion is essential in scientific and engineering applications where precise temperature measurements are required.