A square log with a length of 10 meters is sawed into 5 equal parts, and the surface area is increased by 4 square meters compared with the original one. What is the volume of this square log?
把一根长10米的方木锯成相等的5份，表面积比原来增加4平方米，这根方木的体积是多少．
<gadget id="calculator">4 * 2</gadget>
<output>8</output>

<gadget id="calculator">4 / 8</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">(1/2) * 10</gadget>
<output>5</output>

<result>5</result>