A square tablecloth has a side length of 9 decimeters. Lace should be placed around the tablecloth. How long is the lace?
一块正方形的桌布，边长是9分米．要给桌布的四周镶上花边，花边长多少米？
<gadget id="calculator">9 * 4</gadget>
<output>36</output>

<result>36</result>