How many square centimeters of wrapping paper are needed to wrap three cuboid cartons with a length of 15 cm, a width of 10 cm, and a height of 4 cm?
把3个长15厘米，宽10厘米，高4厘米的长方体纸盒包在一起，至少需要多少平方厘米包装纸．
<gadget id="calculator">15 * 10 * 2</gadget>
<output>300</output>

<gadget id="calculator">4 * 3</gadget>
<output>12</output>

<gadget id="calculator">15 * 12 * 2</gadget>
<output>360</output>

<gadget id="calculator">10 * 12 * 2</gadget>
<output>240</output>

<gadget id="calculator">300 + 360 + 240</gadget>
<output>900</output>

<result>900</result>