Use the three number cards 0, 6, and 9 to count according to the requirements. Choose one, two or three of the three cards, how many different natures can be displayed.
用0、6、9三张数字卡片按要求摆数．从三张卡片中选一张，两张或者三张，可以摆出多少个不同的自然．
<gadget id="calculator">3 + 4 + 4</gadget>
<output>11</output>

<result>11</result>