The thickness of a kind of book is about 25mm, how many centimeters is the total thickness of 8 such books
一种书的厚度约是25毫米，8本这样的书摞起来一共厚约多少厘米
<gadget id="calculator">8 / 10</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">25 * (4/5)</gadget>
<output>20</output>

<result>20</result>