The first class of the fourth grade accounts for (1/3) of the number of students in this grade, the number of the fourth grade students is the whole school (1/5), and the number of the first class of the fourth grade is the whole school.
四年级一班占本年级学生人数的(1/3)，四年级学生人数是全校的(1/5)，四年级一班人数是全校的多少．
<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

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

<gadget id="calculator">(1/5) * (1/3)</gadget>
<output>1/15 = around 0.066667</output>

<result>1/15 = around 0.066667</result>