One addend is increased by 0.2, and the other is also increased by 0.2, how much does their sum increase
一个加数增加0.2，另一个加数也增加0.2，它们的和增加多少
<gadget id="calculator">0.2 + 0.2</gadget>
<output>0.4</output>

<result>0.4</result>