How many even numbers are there in 100-200?
100～200中有多少个偶数．
<gadget id="calculator">200 - 100</gadget>
<output>100</output>

<gadget id="calculator">100 / 2</gadget>
<output>50</output>

<gadget id="calculator">50 + 1</gadget>
<output>51</output>

<result>51</result>