There are 4 types of paper cups, which can hold (1/3) liters, (4/9) liters, (1/5) liters, and (2/7) liters respectively. Xiao Ming pours 2 liters of juice into one of the paper cups, about When it comes to 4 full cups, how many liters of paper cups did he use?
有4中纸杯，分别能装(1/3)升，(4/9)升，(1/5)升，(2/7)升，小明把2升的果汁倒入其中一种纸杯，大约到了4满杯，他用的是多少升的纸杯．
<gadget id="calculator">4 / 9</gadget>
<output>4/9 = around 0.444444</output>

<result>4/9 = around 0.444444</result>