Cut a rectangle with a length of 12 cm and a width of 7 cm into the largest square, what is the remaining area?
把一个长是12厘米，宽是7厘米的长方形剪成一个最大的正方形，余下的面积是多少．
<gadget id="calculator">12 - 7</gadget>
<output>5</output>

<gadget id="calculator">7 * 5</gadget>
<output>35</output>

<result>35</result>