A nurse is preparing to administer magnesium hydroxide 0.85 g PO to a school-age child. How many mg should the nurse administer? (Round the answer to the nearest whole number. Use a leading zero if it applies. Do not use a trailing zero.)

To convert grams to milligrams, the value in grams is multiplied by 1,000. Therefore, to administer magnesium hydroxide 0.85 g PO, the nurse should administer 850 mg. This is because 0.85 grams equals 850 milligrams. When rounding to the nearest whole number, the amount remains 850 mg, as it is already a whole number.