There are 684 students in Chatu Mingde Primary School, 25% of whom are in the sixth grade, and (1/3) of the sixth grade students are girls. How many girls are there in the sixth grade?
扯土明德小学共有学生684名，其中六年级学生占25%，六年级学生中有(1/3)是女生，六年级有多少名女生？
<gadget id="calculator">25 / 100</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">684 * (1/4) * (1/3)</gadget>
<output>57</output>

<result>57</result>