A figure rotated clockwise by 90° with the center point as the rotation point coincides with the number of degrees rotated counterclockwise.
一个图形以中心点为旋转点顺时针旋转90°和逆时针旋转多少°的图形重合．
<gadget id="calculator">360 - 90</gadget>
<output>270</output>

<result>270</result>