There are 20 small cubes with a side length of 1 cm. If you want to arrange them into a slightly larger cube, what is the number of cubes you need?
有20个棱长1cm的小正方体，想摆成稍大一些的正方体，还需要正方体的个数是多少．
<gadget id="calculator">3 * 3 * 3</gadget>
<output>27</output>

<gadget id="calculator">27 - 20</gadget>
<output>7</output>

<result>7</result>