The survival rate of a sapling is 80%. If you want to ensure that 500 saplings survive. So at least how many saplings should be planted.
一种树苗的成活率是80%．如果要保证有500棵树苗成活．那么至少应种下多少棵树苗．
<gadget id="calculator">80 / 100</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">500 / (4/5)</gadget>
<output>625</output>

<result>625</result>