Xiao Li reads a story book, she reads 10% of the whole book on the first day, and then reads 21 pages every day, and she just finishes reading it in another 6 days. How many pages does this book have?
小丽读一本故事书，第一天读了全书的10%，以后每天读21页，又读了6天正好读完．这本书一共有多少页？
<gadget id="calculator">21 * 6</gadget>
<output>126</output>

<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">126 / (9/10)</gadget>
<output>140</output>

<result>140</result>