The uncle earns 3,600 yuan a month, and the part after deducting 2,000 yuan is required to pay personal income tax at a rate of 40%. How much should the uncle pay in personal income tax a month?
叔叔一个月收入3600元，按规定减去2000元后的部分按40%的税率缴纳个人所得税，叔叔一个月应该缴纳多少元个人所得税．
<gadget id="calculator">3_600 - 2_000</gadget>
<output>1_600</output>

<gadget id="calculator">40 / 100</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">1_600 * (2/5)</gadget>
<output>640</output>

<result>640</result>