In September, October and November, Xinxin Store sold an average of 19 cartons of milk per day. So how many cartons of milk have been sold in total in the past three months?
欣欣商店9月、10月、11月平均每天出售牛奶19箱．那么这三个月一共出售牛奶多少箱？
<gadget id="calculator">30 + 31 + 30</gadget>
<output>91</output>

<gadget id="calculator">19 * 91</gadget>
<output>1_729</output>

<result>1_729</result>