The original price of a commodity is 81 yuan, and now it is sold at a 10% discount. How much cheaper is the current price than before?
一件商品原来的售价是81元，现在打九折出售．现在的售价比原来便宜多少元？
<gadget id="calculator">90 / 100</gadget>
<output>9/10 = around 0.9</output>

<gadget id="calculator">81 * (9/10)</gadget>
<output>729/10 = around 72.9</output>

<gadget id="calculator">81 - (729/10)</gadget>
<output>81/10 = around 8.1</output>

<result>81/10 = around 8.1</result>