The number of boys in the fifth grade is 2/3 of the number of girls, so the number of boys is the number of the whole grade.
五年级男生人数是女生人数的(2/3)，那么男生人数是全年级人数的多少．
<gadget id="calculator">2 / 3</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">1 + (2/3)</gadget>
<output>5/3 = around 1.666667</output>

<gadget id="calculator">(2/3) / (5/3)</gadget>
<output>2/5 = around 0.4</output>

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