Arrange the three cards with 5, 6, and 4 randomly into a three-digit number, then what is the possibility that the three-digit number is less than 500?
把写着5、6、4的三张卡片任意摆成一个三位数，那么这个三位数小于500的可能性是多少．
<gadget id="calculator">3 * 2 * 1</gadget>
<output>6</output>

<gadget id="calculator">2 / 6</gadget>
<output>1/3 = around 0.333333</output>

<result>1/3 = around 0.333333</result>