The position reached by an object rotating 90° clockwise around point O is equivalent to how many degrees it rotates counterclockwise around point O.
一个物体绕O点顺时针旋转90°到达的位置，相当于绕O点逆时针旋转多少度．
<gadget id="calculator">360 - 90</gadget>
<output>270</output>

<result>270</result>