The water lilies in the pond double in size every day. If the whole pond can be grown on the 10th day, how much can it grow to the whole pond on the 9th day.
池塘里睡莲的面积每天长大一倍．如果第10天就可以长满整个池塘，那么第9天长到整个池塘的多少．
<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<result>1/2 = around 0.5</result>