Splitting a 2m long round end along its diameter into two parts with equal volume increases the surface area by 1.6m**2. What was the volume of the original log?
将一根长2m的圆末沿着直径劈成体积相等的两部分，表面积增加了1.6m**2．原来这根原木的体积是多少？
<gadget id="calculator">1.6 / 2 / 2</gadget>
<output>0.4</output>

<gadget id="calculator">0.4 / 2</gadget>
<output>0.2</output>

<gadget id="calculator">0.2 ** 2</gadget>
<output>0.04</output>

<gadget id="calculator">3.14 * 0.04 * 2</gadget>
<output>0.2512</output>

<result>0.2512</result>