Cotton planting area accounts for 40% of the total planting area. When a fan representing this planting area is drawn on the sector chart, what is the central angle of the circle?
棉花种植面积占总种植面积的40%，在扇形统计图上画出表示这一种植面积的扇形时，其圆心角是多少度．
<gadget id="calculator">40 / 100</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">360 * (2/5)</gadget>
<output>144</output>

<result>144</result>