To administer methylprednisolone succinate to a child who weighs 42 kg, the nurse  should know how many mL to give with each dose. The prescription is for 1.5 mg/kg/day  intravenously in divided doses every 6 hours. To calculate the dose in mg, multiply the  weight in kg by the dose in mg/kg. For example, 42 kg x 1.5 mg/kg = 63 mg. To calculate  the frequency of administration, divide the daily dose by the number of times per day.  For example, 63 mg / 4 times per day = 15.75 mg per dose. To calculate the volume in  mL, divide the dose in mg by the concentration in mg/mL. For example, 15.75 mg / 40  mg/mL = 0.39375 mL. If rounding is required, round to the nearest tenth. Therefore, the  nurse should administer 0.4 mL with each dose.