Hi - first of all I want to say to you, GO FOR IT!! It sounds like you're off to a great start. I am 52 and started nursing school at 50. With God's grace, I will graduate in December 16 with my ADN-RN degree! There is no dosage calculations on the entrance HESI when applying for nursing school. It's basic math: decimals, fractions, etc. Once you start school and do your exit HESI tests after certain courses, then the dosage calculation will be there. There are some good books for studying HESI and there are some good websites where you can take some free practice exams. Good luck to you!!