A square iron sheet with a side length of 8.4 cm, and a piece of iron sheet with an area of 40.5 square centimeters is dug out of it, what is the area of the remaining iron sheet? ?
一个边长为8.4厘米的正方形铁皮，从中挖去一块面积为40.5平方厘米的铁皮，剩下的铁皮面积是多少？？
<gadget id="calculator">8.4 * 8.4</gadget>
<output>70.56</output>

<gadget id="calculator">70.56 - 40.5</gadget>
<output>30.06</output>

<result>30.06</result>