Hold investment fairs for companies A, B, C, and D. This meeting requires each two companies to negotiate only once. In order to ensure that two companies negotiate three times, at least how many such fairs should be held this year.
召开甲、乙、丙、丁四个公司的投资洽谈会，这场会议要求每两个公司都只洽谈一次，为保证有两个公司洽谈3次，今年至少要召开多少场这样的洽谈会．
<gadget id="calculator">3 / 2</gadget>
<output>3/2 = around 1.5</output>

<gadget id="calculator">4 * (3/2)</gadget>
<output>6</output>

<gadget id="calculator">6 + 2</gadget>
<output>8</output>

<result>8</result>