There are two circles, big and small. The radius of the big circle is 5 cm, and the radius of the small circle is 4 cm. What is the area of the small circle equal to the area of the big circle?
有大、小两个圆，大圆半径是5厘米，小圆半径是4厘米，小圆面积是大圆面积的多少
<gadget id="calculator">4 ** 2</gadget>
<output>16</output>

<gadget id="calculator">5 ** 2</gadget>
<output>25</output>

<gadget id="calculator">16 / 25</gadget>
<output>16/25 = around 0.64</output>

<result>16/25 = around 0.64</result>