4.5*0.4+0.4*5.5．
4.5*0.4+0.4*5.5．
<gadget id="calculator">4.5 * 0.4</gadget>
<output>1.8</output>

<gadget id="calculator">0.4 * 5.5</gadget>
<output>2.2</output>

<gadget id="calculator">1.8 + 2.2</gadget>
<output>4</output>

<result>4</result>