Xiaoqiang's house is 1 kilometer away from grandma's house. One day he took a dog from home to grandma's house, the dog ran to grandma's house as soon as he set off, and returned immediately after arriving at grandma's house, when he came back and met Xiaoqiang, it ran to grandma's house again, and the dog kept running back and forth ． It is known that Xiaoqiang walks 50 meters per minute, and the dog runs 200 meters per minute. When Xiaoqiang arrived at his grandmother's house, how many meters did the dog run in total?
小强家距外婆家1千米．一天他带一条狗，从家去外婆家，一出发狗就跑向外婆家，到外婆家后又立即回，回来遇到小强时，它又跑向外婆家，狗就这样来回不停的跑．已知小强每分钟走50米，狗每分钟跑200米，问小强到外婆家时，狗共跑了多少米路？
<gadget id="calculator">1_000 / 50</gadget>
<output>20</output>

<gadget id="calculator">200 * 1 * 20</gadget>
<output>4_000</output>

<result>4_000</result>