A rectangle of paper is 18 cm long and 15 cm wide. Cut out the largest square from this piece of paper, what is the remaining area?
一个长方形纸片长是18厘米，宽是15厘米．从这张纸片里剪去一个最大的正方形，剩下的面积是多少．
<gadget id="calculator">18 - 15</gadget>
<output>3</output>

<gadget id="calculator">15 * 3</gadget>
<output>45</output>

<result>45</result>