The survival rate of a batch of fruit trees is 90%, and if 180 trees are to survive, at least how many trees must be planted.
一批果树的成活率是90%，要成活180棵，至少要栽种多少棵．
<gadget id="calculator">90 / 100</gadget>
<output>9/10 = around 0.9</output>

<gadget id="calculator">180 / (9/10)</gadget>
<output>200</output>

<result>200</result>