The price of a commodity is first increased by 10% and then decreased by 10%. How much is the current price equal to the original price?
一种商品先提价10%又降价10%．这时现价相当于原价的多少
<gadget id="calculator">10 / 100</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">1 + (1/10)</gadget>
<output>11/10 = around 1.1</output>

<gadget id="calculator">1 - (1/10)</gadget>
<output>9/10 = around 0.9</output>

<gadget id="calculator">1 * (11/10) * (9/10)</gadget>
<output>99/100 = around 0.99</output>

<result>99/100 = around 0.99</result>