Mrs. Li brought 900 yuan to buy milk for the kindergarten, bought 16 boxes, 55 yuan per box, how much money is left?
李老师带900元钱为幼儿园买牛奶，买了16箱，每箱55元，还剩下多少元？
<gadget id="calculator">55 * 16</gadget>
<output>880</output>

<gadget id="calculator">900 - 880</gadget>
<output>20</output>

<result>20</result>