Put 20 red, yellow and blue colored balls in the pocket, the probability of touching the red ball is (1/4), how many red balls should be put.
在口袋里放20个红、黄、蓝的彩球，摸到红球的可能性是(1/4)，应放多少个红球．
<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">20 * (1/4)</gadget>
<output>5</output>

<result>5</result>