In the same circle, the diameter is 4 decimeters, what is the radius in centimeters
同一个圆中，直径是4分米，半径是多少厘米
<gadget id="calculator">4 / 2</gadget>
<output>2</output>

<gadget id="calculator">2 * 10</gadget>
<output>20</output>

<result>20</result>