There are 45 cows in a dairy farm, and each cow eats 12 kg of grass per day. According to this calculation, how many kilograms of grass did these cows eat in February this year?
奶牛场有45头奶牛，每头奶牛每天吃草12千克．照这样计算，这些奶牛今年二月份一共吃草多少千克？
<gadget id="calculator">12 * 45 * 29</gadget>
<output>15_660</output>

<result>15_660</result>