How many centimeters is the circumference of a circle with a radius of 4 cm greater than the circumference of a circle with a diameter of 6 cm?
半径为4厘米的圆比直径为6厘米的圆的周长多多少厘米．
<gadget id="calculator">3.14 * 4 * 2</gadget>
<output>25.12</output>

<gadget id="calculator">3.14 * 6</gadget>
<output>18.84</output>

<gadget id="calculator">25.12 - 18.84</gadget>
<output>6.28</output>

<result>6.28</result>