Adds up the density of a breathing mix at depth from the partial pressure of each gas in it.
The formula: Sum of PP x (O2 1.4102, N2 1.2346, He 0.1764). 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.