The Health Care Provider orders Phenobarbital 3 milligrams per kilogram per day divided in two doses. Calculate a single dose for a newborn that weighs 3 kilograms. Do not round your answer.

Step 1 is: Calculate the total daily dose in milligrams by multiplying the ordered dose (3 mg/kg/day) by the weight in kilograms (3 kg). 3 mg/kg/day × 3 kg = 9 mg/day. Step 2 is: Calculate the single dose by dividing the total daily dose (9 mg/day) by the number of doses per day (2 doses). 9 mg/day ÷ 2 doses = 4.5 mg/dose. The final calculated answer is 4.5 mg.