The nurse is initiating a prescription for IV dextrose 2.5% in 0.45% sodium chloride (D, 0.5% NS) at 45 mL/hour for a child with dehydration. The nurse attaches a volume-control administration set with a microdrop chamber to the bag of solution. How many microdrops/minute should the nurse regulate the infusion? (Enter the numerical value only. If rounding is required, round to the nearest whole number.)