There are 840 students in Guangming Primary School. The fifth grade accounts for 2/7 of the school's students, and the fifth grade girls account for this grade (5/12). How many girls are there in the fifth grade?
光明小学有学生840人，五年级占学校学生的(2/7)，五年级的女生占本年级的(5/12)，五年级有女生多少人？
<gadget id="calculator">2 / 7</gadget>
<output>2/7 = around 0.285714</output>

<gadget id="calculator">5 / 12</gadget>
<output>5/12 = around 0.416667</output>

<gadget id="calculator">840 * (2/7) * (5/12)</gadget>
<output>100</output>

<result>100</result>