There is a lawn, the area of the lawn doubles every day. After ten days, the area of the lawn reaches 84 square meters. What is the area of the lawn on the seventh day?
有一草坪，每天生长的面积扩大2倍，十天后草坪的面积达84平方米，问第七天草坪的面积是多少．
<gadget id="calculator">84 / 2</gadget>
<output>42</output>

<gadget id="calculator">42 / 2</gadget>
<output>21</output>

<gadget id="calculator">21 / 2</gadget>
<output>21/2 = around 10.5</output>

<result>21/2 = around 10.5</result>