Cong Cong started to practice big characters at 2:10 pm on Sunday, and ended at 2:40 pm, practicing 3 big characters per minute, so how many big characters did Congcong practice in total?
聪聪星期天从下午2：10开始练大字，到2：40结束，每分钟练3个大字，那么聪聪一共练了多少个大字？
<gadget id="calculator">30 * 3</gadget>
<output>90</output>

<result>90</result>