A jacket is 90 yuan, how much is the selling price after 10% discount?
一件外套90元，打九折后的售价是多少元．
<gadget id="calculator">90 / 100</gadget>
<output>9/10 = around 0.9</output>

<gadget id="calculator">90 * (9/10)</gadget>
<output>81</output>

<result>81</result>