A book has 100 pages, Xiao Ming has read 20 pages, how many times the number of pages he has not read is the number of pages he has read?
一本书100页，小明看了20页，没看的页数是看过页数的多少倍？
<gadget id="calculator">100 - 20</gadget>
<output>80</output>

<gadget id="calculator">80 / 20</gadget>
<output>4</output>

<result>4</result>