While the earth is constantly revolving around the sun, it is also constantly rotating from west to east. It takes 1 day to rotate once, (1/4) how many degrees the earth rotates from west to east.
地球在不停地绕太阳旋转的同时，自己也在不停地自西向东自转，转动一周是1天，(1/4)天地球自西向东转多少度．
<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">360 * (1/4)</gadget>
<output>90</output>

<result>90</result>