Calculate with a simple method: 3.69*0.8+6.31*0.8-3.8.
用简便方法计算：3.69*0.8+6.31*0.8-3.8．
<gadget id="calculator">3.69 * 0.8</gadget>
<output>2.952</output>

<gadget id="calculator">6.31 * 0.8</gadget>
<output>5.048</output>

<gadget id="calculator">5.048 - 3.8</gadget>
<output>1.248</output>

<gadget id="calculator">2.952 + 1.248</gadget>
<output>4.2</output>

<result>4.2</result>