A certain elementary school originally planned to send 15 students to participate in the district table tennis competition, but actually sent 21 students. How many percent were the actual number of students more than the number planned?
某小学原计划派出15名同学参加全区学生兵乓球比赛，实际上派出了21名同学，实际派出的人数比计划派出的人数多了百分之几？
<gadget id="calculator">21 - 15</gadget>
<output>6</output>

<gadget id="calculator">6 / 15</gadget>
<output>2/5 = around 0.4</output>

<result>2/5 = around 0.4</result>