I belive both are... I am taking the class now...
Answer:
In order to express the results as a percent, divide the nutrient content (which is expressed in ppm) by 10,000. For example, if the reported value for P2O5 is 2,690 ppm, the calculation to convert to percent would be: 2,690 ppm ÷ 10,000 = 0.269%.
12 inches=1 foot is the answer I believe.