The cube packing box is 40 cm long, how many m**2 of cardboard is needed to make 50 such cartons.
正方体包装箱长40厘米，做50个这样的纸箱，需用纸板多少m**2．
<gadget id="calculator">40 / 100</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">(2/5) * (2/5) * 6 * 50</gadget>
<output>48</output>

<result>48</result>