The volume ratio of "Mathematics World" and "Mathematics Story" is 4:6, how much more volumes of "Mathematics Story" than "Mathematics World".
《数学天地》和《数学故事》册数的比是4：6，《数学故事》的册数比《数学天地》的册数多多少．
<gadget id="calculator">6 - 4</gadget>
<output>2</output>

<gadget id="calculator">2 / 4</gadget>
<output>1/2 = around 0.5</output>

<result>1/2 = around 0.5</result>