A commodity is sold at a 10% discount. How many pieces can you buy with the money you used to buy 18 pieces of this commodity?
一种商品打九折出售，原来买18件这种商品的钱，现在能买多少件．
<gadget id="calculator">90 / 100</gadget>
<output>9/10 = around 0.9</output>

<gadget id="calculator">1 / (9/10)</gadget>
<output>10/9 = around 1.111111</output>

<gadget id="calculator">18 * (10/9)</gadget>
<output>20</output>

<result>20</result>