Xiaodong uses a small square with a side length of 1 cm to study the area of a rectangular piece of paper. He only placed small squares along one length and one width of the rectangle, and used exactly 8 of them. What is the maximum area of this rectangle in square centimeters?
小东用边长为1厘米的小正方形研究一张长方形纸的面积．他只沿着长方形的一条长和一条宽摆小正方形，正好用了8个．这个长方形的面积最大是多少平方厘米．
<gadget id="calculator">4 * 5</gadget>
<output>20</output>

<result>20</result>