1+1.1-1.2+1.3...+1.9．
1+1.1-1.2+1.3…+1.9．
<gadget id="calculator">1.2 - 1.1</gadget>
<output>0.1</output>

<gadget id="calculator">1.4 - 1.3</gadget>
<output>0.1</output>

<gadget id="calculator">1.6 - 1.5</gadget>
<output>0.1</output>

<gadget id="calculator">1.8 - 1.7</gadget>
<output>0.1</output>

<gadget id="calculator">1 - 0.1 - 0.1 - 0.1 - 0.1</gadget>
<output>0.6</output>

<gadget id="calculator">0.6 + 1.9</gadget>
<output>2.5</output>

<result>2.5</result>