Put 7 yellow balls, 2 white balls, and 1 red ball into a box. Draw out one at random each time, and put it back into the box after touching it. If you touch it 100 times in this way, the number of white balls drawn out will account for approximately the total number of times.
把7个黄球，2个白球，l个红球放人盒子里．每次任意摸出1个，摸后放回盒中，这样摸100次，摸出白球的次数大约占总数的多少．
<gadget id="calculator">7 + 2 + 1</gadget>
<output>10</output>

<gadget id="calculator">2 / 10 / 100</gadget>
<output>1/500 = around 0.002</output>

<gadget id="calculator">100 * (1/500)</gadget>
<output>1/5 = around 0.2</output>

<result>1/5 = around 0.2</result>