Corrects a CO2 tube reading taken at pressure: the true percentage is the scale reading divided by the absolute pressure.
The formula: True % = scale/absolute; mbar = scale x 10. Change any box and the full working updates. For study only, never for dive planning.
The IMCA ADS, BDS and LST papers ask this as a four-option question, with a calculator on screen. A free account gives you 15 practice questions for each exam, each with the worked answer and the document it comes from.