A school has a total of 1680 students, of which boys account for 40% of the total number of students in the school. How many boys should be recruited to make the number of boys account for 50% of the total number of students in the school?
某校共有学生1680人，其中男生占全校人数的40%，要使男生人数占全校人数的50%，还要招多少名男生．
<gadget id="calculator">40 / 100</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">1 - (2/5)</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">50 / 100</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">1 - (1/2)</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">(3/5) / (1/2)</gadget>
<output>6/5 = around 1.2</output>

<gadget id="calculator">1_680 * (6/5)</gadget>
<output>2_016</output>

<gadget id="calculator">2_016 - 1_680</gadget>
<output>336</output>

<result>336</result>