In this course we review commonly misunderstood pharmaceutical concepts related to ratios, proportions, solid and liquid dilutions, molar masses, displacement values, aliquots and alligation. My aim is to help you gain confidence in the application of these concepts so that you can enhance your accuracy in the measurement of, prescribing and dosing dosing of patient medication, thus not only enhancing the therapeutic benefits to your patients; but also minimising the risk of harm.