A batch of saplings were planted in Fenglin Village. It is known that the survival rate of these saplings is between 70% and 80%. If 4,200 saplings are to be guaranteed to survive, how many saplings need to be planted?
丰林村栽种了一批树苗，已知这批树苗的成活率在70%～80%之间．如果要保证有4200棵树苗成活，需要种多少棵树苗？
<gadget id="calculator">70 / 100</gadget>
<output>7/10 = around 0.7</output>

<gadget id="calculator">4_200 / (7/10)</gadget>
<output>6_000</output>

<result>6_000</result>