There is a pile of yellow sand on the pier. A truck can transport 6 tons at a time, and it has been transported 13 times. There are still 500 tons of yellow sand that have not been transported away. How many tons of yellow sand was there in the pier?
码头有堆黄沙．一辆卡车一次能运走6吨，已经运走了13次．还剩下500吨的黄沙没运走．码头原来有多少吨黄沙？
<gadget id="calculator">6 * 13</gadget>
<output>78</output>

<gadget id="calculator">78 + 500</gadget>
<output>578</output>

<result>578</result>