Lizhuang planted 450 trees last year, and 405 survived. According to this calculation, to ensure the survival of 450 trees this year, at least how many trees should be planted.
李庄去年植树450棵，成活了405棵．照这样计算，今年要保证成活450棵，至少要植树多少棵．
<gadget id="calculator">405 / 450</gadget>
<output>9/10 = around 0.9</output>

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

<gadget id="calculator">(9/10) * 1</gadget>
<output>9/10 = around 0.9</output>

<gadget id="calculator">450 / (9/10)</gadget>
<output>500</output>

<result>500</result>