Put 7 red balls and 3 yellow balls in the same pocket, draw out 1 ball at random, and then put it into the pocket. If you touch 20 times in this way, the number of times you touch the red ball accounts for approximately the total number of times.
把7个红球和3个黄球装在同一个口袋中任意摸出1个球，然后再放入口袋．照这样摸20次，摸出红球的次数大约占总次数的多少．
<gadget id="calculator">7 + 3</gadget>
<output>10</output>

<gadget id="calculator">7 / 10</gadget>
<output>7/10 = around 0.7</output>

<result>7/10 = around 0.7</result>