How many meters of lace are needed to surround a tablecloth with a side length of 10 decimeters?
要给一块边长10分米的桌布围上花边，需要多少米的花边？
<gadget id="calculator">10 * 4</gadget>
<output>40</output>

<gadget id="calculator">40 / 10</gadget>
<output>4</output>

<result>4</result>