If the circumference of a circle is 25.12 cm, if its diameter is increased by 2 cm, how much will its area increase?
一个圆的周长是25.12厘米，将它的直径增加2厘米，它的面积增加了多少．
<gadget id="calculator">25.12 / 3.14 / 2</gadget>
<output>4</output>

<gadget id="calculator">2 / 2</gadget>
<output>1</output>

<gadget id="calculator">4 + 1</gadget>
<output>5</output>

<gadget id="calculator">3.14 * 5 * 5</gadget>
<output>78.5</output>

<gadget id="calculator">3.14 * 4 * 4</gadget>
<output>50.24</output>

<gadget id="calculator">78.5 - 50.24</gadget>
<output>28.26</output>

<result>28.26</result>