After cutting a cylinder into the largest cone, the volume is reduced by 2.8 cubic decimeters. What is the volume of the original cylinder?
把一个圆柱削成一个最大的圆锥后，体积减少了2.8立方分米，原来的圆柱体积是多少立方分米．
<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">2.8 / (2/3)</gadget>
<output>4.2</output>

<result>4.2</result>