How many m**2 boards are needed to make 10 cubic wooden boxes without a lid whose edge length is 30cm?
做10个棱长是30cm的无盖正方体木盒，至少需要多少m**2的木板？
<gadget id="calculator">30 / 100</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">(3/10) * (3/10) * 5 * 10</gadget>
<output>9/2 = around 4.5</output>

<result>9/2 = around 4.5</result>