A book has 150 pages in total, how many typefaces are used to number the pages of this book?
一本书共有150页，编排这本书的页码要用到多少个铅字．
<gadget id="calculator">90 * 2</gadget>
<output>180</output>

<gadget id="calculator">51 * 3</gadget>
<output>153</output>

<gadget id="calculator">9 + 180 + 153</gadget>
<output>342</output>

<result>342</result>