A mouse eats 10 grains of rice a day, and a cat can catch 6 mice a day. Following this calculation, how many grains of rice can a cat exchange for a week?
一只老鼠一天吃10粒米，一只猫一天能抓6只老鼠．接这样计算，一只猫一个星期能换回几粒米？
<gadget id="calculator">10 * 6 * 7</gadget>
<output>420</output>

<result>420</result>