A product with an original price of 90 yuan is sold at a 10% discount, how much cheaper it is.
一件原价90元的商品打九折出售，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">90 * (1/10)</gadget>
<output>9</output>

<result>9</result>