On Arbor Day, 250 trees were planted, and 240 survived. What is the non-survival rate?
植树节种植了250棵树，成活了240棵，未成活率是多少．
<gadget id="calculator">250 - 240</gadget>
<output>10</output>

<gadget id="calculator">10 / 250</gadget>
<output>1/25 = around 0.04</output>

<gadget id="calculator">100 / 100</gadget>
<output>1</output>

<gadget id="calculator">(1/25) * 1</gadget>
<output>1/25 = around 0.04</output>

<result>1/25 = around 0.04</result>