There are 10 red balls, 8 green balls and some black balls in a box, and each time a ball is taken out of it, the probability of getting a green ball is less than (1/3), then at least how many black balls are there.
在一个盒子中有10个红球，8个绿球和一些黑球，每次从里面拿出一个球，结果拿出绿球的可能性小于(1/3)，那么至少有多少黑球．
<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">8 / (1/3)</gadget>
<output>24</output>

<gadget id="calculator">24 - 10 - 8</gadget>
<output>6</output>

<gadget id="calculator">6 + 1</gadget>
<output>7</output>

<result>7</result>