If a log 15 meters long is cut into 3 small logs, the surface area is increased by 28 square decimeters, what is the original volume of the log in cubic meters?
把一根长15米的圆木截成3段小圆木，表面积增加28平方分米，这根圆木原来的体积是多少立方米．
<gadget id="calculator">28 / 4</gadget>
<output>7</output>

<gadget id="calculator">10 / 1_000</gadget>
<output>1/100 = around 0.01</output>

<gadget id="calculator">7 * 15 * (1/100)</gadget>
<output>21/20 = around 1.05</output>

<result>21/20 = around 1.05</result>