A number of students are arranged in a hollow square with 5 layers. There are 12 students on each side of the outermost layer. How many students are there?
有学生若干人，排成5层的中空方阵，最外层每边人数是12人，问有多少个学生．
<gadget id="calculator">12 - 5</gadget>
<output>7</output>

<gadget id="calculator">7 * 5 * 4</gadget>
<output>140</output>

<result>140</result>