There is a stop sign at the gate of the school. Both the No. 6 and No. 9 buses depart from here, but the No. 6 bus departs every 12 minutes, and the No. 9 bus departs every 18 minutes. After the two buses depart at the same time, at least How many minutes did it take for the two-way car to start for the second time?
学校门口有个站牌，6路车和9路车都从这里发车，但是6路车每12分钟发一次车，9路车每18分钟发一次车，这两路公交车同时发车以后，至少过多少分钟两路车才第二次发车？
<gadget id="calculator">2 * 2 * 3 * 3</gadget>
<output>36</output>

<result>36</result>