The radius of a circle is 6 decimeters. If the radius is reduced by 2 decimeters, how much will the circumference be reduced by?
一个圆的半径6分米，如果半径减少2分米，周长减少多少分米．
<gadget id="calculator">3.14 * 6 * 2</gadget>
<output>37.68</output>

<gadget id="calculator">6 - 2</gadget>
<output>4</output>

<gadget id="calculator">3.14 * 4 * 2</gadget>
<output>25.12</output>

<gadget id="calculator">37.68 - 25.12</gadget>
<output>12.56</output>

<result>12.56</result>