Simple calculation: 2.25*2.8-12.5*0.28.
简便计算：2.25*2.8-12.5*0.28．
<gadget id="calculator">2.25 * 2.8</gadget>
<output>6.3</output>

<gadget id="calculator">12.5 * 0.28</gadget>
<output>3.5</output>

<gadget id="calculator">6.3 - 3.5</gadget>
<output>2.8</output>

<result>2.8</result>