18 mg. per mil. times 4 mil. equals 72 mg. of nic total. Correct?Right now I'm vaping pinkman with self-added 18mg of nicotine, I take about 100 drags a day which is half of my tank (big tank) and I want to know if it's safe to vape everyday 18mg juice with 100 drags a day an average. So, is it OK/healthy? And a second question: I have 18mg of nicotine in 60ml juicy bottle, so how much is nicotine in one 4ml tank?