For saplings with a survival rate of 90%, how many saplings need to be planted to survive 360.
成活率是90%的树苗，要成活360棵，需栽多少棵树苗．
<gadget id="calculator">90 / 100</gadget>
<output>9/10 = around 0.9</output>

<gadget id="calculator">360 / (9/10)</gadget>
<output>400</output>

<result>400</result>