I am confused on a 1ml insulin syringe that has 100 units on it there are marks of 10,20,30,40,50,60,70,80,90,100 on it so when someone says dosage is 3 marks on an U100 insulin syringe does it mean the mark 30 labeled on the syringe is the 3 mark. Sorry to ask this but very confusing and no one has explained this yet.