Use three cuboids whose length, width and height are 5 cm, 3 cm and 1 cm respectively to form a large cuboid with the smallest surface area. What is the surface area of this large cuboid?
用三个长、宽、高分别是5厘米、3厘米、1厘米的长方体拼成一个表面积最小的大长体，这个大长方体的表面积是多少．
<gadget id="calculator">5 * 3</gadget>
<output>15</output>

<gadget id="calculator">5 * 1</gadget>
<output>5</output>

<gadget id="calculator">3 * 1</gadget>
<output>3</output>

<gadget id="calculator">15 + 5 + 3</gadget>
<output>23</output>

<gadget id="calculator">23 * 2 * 3</gadget>
<output>138</output>

<gadget id="calculator">5 * 3 * 4</gadget>
<output>60</output>

<gadget id="calculator">138 - 60</gadget>
<output>78</output>

<result>78</result>