To celebrate the National Day, the students arranged classrooms and bought 150 red balloons. The number of yellow balloons bought was 6 times that of the red balloons. How many yellow balloons did they buy?
庆祝国庆，同学们布置教室买来150个红气球，买来的黄气球的个数是红气球的6倍，买来黄气球多少个？
<gadget id="calculator">150 * 6</gadget>
<output>900</output>

<result>900</result>