A pile of coal consumes (2/9) of the total amount every day, and how much of the total amount is used in 4 days.
一堆煤，每天用去总量的(2/9)，4天用去总量的多少．
<gadget id="calculator">2 / 9</gadget>
<output>2/9 = around 0.222222</output>

<gadget id="calculator">(2/9) * 4</gadget>
<output>8/9 = around 0.888889</output>

<result>8/9 = around 0.888889</result>