2.3 meters of a rope are used up, and there are 1.8 meters left. How long is the rope?
一根绳子用去2.3米，还剩下1.8米，这根绳子原来有多长．
<gadget id="calculator">2.3 + 1.8</gadget>
<output>4.1</output>

<result>4.1</result>