The original price of a book is 9.2 yuan, and now it is sold at 10% off the original price. How much cheaper is it?
一本图书原价9.2元，现在按原价打九折出售，便宜了多少元？
<gadget id="calculator">90 / 100</gadget>
<output>9/10 = around 0.9</output>

<gadget id="calculator">1 - (9/10)</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">9.2 * (1/10)</gadget>
<output>0.92</output>

<result>0.92</result>