After the price of a certain item has been reduced by 10% twice in a row, the price is 81 yuan. So what is the original price of this item.
某种物品连续两次降价10%后，售价81元．那么这种物品的原价是多少元．
<gadget id="calculator">10 / 100</gadget>
<output>1/10 = around 0.1</output>

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

<gadget id="calculator">81 / (9/10) / (9/10)</gadget>
<output>100</output>

<result>100</result>