How long should the packing tape be at least to bind a cuboid book with a length of 20 cm, a width of 15 cm, and a height of 30 cm? (neglected at joints)
用包装带扎一根长20厘米、宽15厘米、高30厘米的长方体书籍，至少要用多长的包装带？(接头处忽略不计)
<gadget id="calculator">20 * 2</gadget>
<output>40</output>

<gadget id="calculator">15 * 4</gadget>
<output>60</output>

<gadget id="calculator">30 * 2</gadget>
<output>60</output>

<gadget id="calculator">40 + 60 + 60</gadget>
<output>160</output>

<result>160</result>