There are two cannons aiming at the target at the same time, and the probability that any one cannon will hit is 0.6, what is the probability that both cannons will hit the target?
有两门大炮同时瞄准目标，任何一门大炮命中的概率都是0.6，那么两门大炮都命中的概率是多少．
<gadget id="calculator">1 - 0.6</gadget>
<output>0.4</output>

<gadget id="calculator">0.4 * 0.4</gadget>
<output>0.16</output>

<gadget id="calculator">1 - 0.16</gadget>
<output>0.84</output>

<result>0.84</result>