There are only 4 red balls in the pocket, and one is randomly touched, so that the possibility of drawing a red ball is (1/6), how many balls of other colors must be put in the pocket.
口袋里只有4个红球，任意摸1个，要使摸出红球的可能性为(1/6)，还要往口袋里放多少个其它颜色的球．
<gadget id="calculator">1 / 6</gadget>
<output>1/6 = around 0.166667</output>

<gadget id="calculator">4 / (1/6)</gadget>
<output>24</output>

<gadget id="calculator">24 - 4</gadget>
<output>20</output>

<result>20</result>