The swimming pool is 50 meters long. Xiaoqiang swims 9 back and forth each time. How many meters does he swim each time?
游泳池长50米，小强每次都游9个来回，他每次游多少米？
<gadget id="calculator">50 * 9 * 2</gadget>
<output>900</output>

<result>900</result>