A stack of 100 exercise books is about 30 centimeters high, and 100 million such exercise books are stacked together about how many centimeters high.
一种练习本100本叠放在一起大约高30厘米，一亿本这样的练习本叠放在一起大约高多少厘米．
<gadget id="calculator">30 / 100</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">(3/10) * 100_000_000</gadget>
<output>30_000_000</output>

<result>30_000_000</result>