During the Spring Festival, 6 students each sent a text message to other students to express their greetings, so how many text messages did they send in total?
有6位同学在春节期间，每人都给其他同学发一条短信表示问候，那么他们一共发了多少条短信．
<gadget id="calculator">6 - 1</gadget>
<output>5</output>

<gadget id="calculator">6 * 5</gadget>
<output>30</output>

<result>30</result>