If a cylindrical steel billet is cut into the largest cone, 2.6 cubic centimeters need to be cut off. What is the volume of the cylinder before cutting.
一个圆柱形钢胚，削成一个最大的圆锥，需削去2.6立方厘米，未削前圆柱的体积是多少立方厘米．
<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">2.6 / (2/3)</gadget>
<output>3.9</output>

<result>3.9</result>