Mom typed a manuscript, and typed 10% of the whole book in the first two days. According to this calculation, how many days will it take to type the rest?
妈妈打一本书稿，前2天打了全书的10%，照这样计算，余下部分还要打多少天？
<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">(1/10) / 2</gadget>
<output>1/20 = around 0.05</output>

<gadget id="calculator">(9/10) / (1/20)</gadget>
<output>18</output>

<result>18</result>