log with a length of 5 meters is sawn into 3 pieces, and the surface area increases by 50 square decimeters. What is the original volume of the log?
一根长5米的圆木，锯成3段后，表面积增加了50平方分米，这根原木原来的体积是多少？
<gadget id="calculator">50 / 4 / 100</gadget>
<output>1/8 = around 0.125</output>

<gadget id="calculator">(1/8) * 5</gadget>
<output>5/8 = around 0.625</output>

<result>5/8 = around 0.625</result>