Equation calculation: 0.15*1.9+8.1*0.15.
递等式计算：0.15*1.9+8.1*0.15．
<gadget id="calculator">0.15 * 1.9</gadget>
<output>0.285</output>

<gadget id="calculator">8.1 * 0.15</gadget>
<output>1.215</output>

<gadget id="calculator">0.285 + 1.215</gadget>
<output>1.5</output>

<result>1.5</result>