A batch of flour is sold (1/3), leaving 420 kg. How many kilograms is this batch of flour?
一批面粉卖出(1/3)，还剩420千克．这批面粉共多少千克？
<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">1 - (1/3)</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">420 / (2/3)</gadget>
<output>630</output>

<result>630</result>