Since January 1, 2006, the state has promulgated a new personal income tax collection method. According to regulations: the part of the monthly personal income exceeding 1,600 yuan shall be subject to personal income tax at a rate of 5%. Xiao Ming's father's monthly salary is 2100 yuan, how much should he pay personal income tax?
自2006年1月1日以来，国家颁布了新的个人所得税征收方法．按照规定：每月的个人收入超过1600元的部分，应按照5%的税率缴纳个人所得税．小明的爸爸本月工资是2100元，他应该缴纳个人所得税多少元？
<gadget id="calculator">2_100 - 1_600</gadget>
<output>500</output>

<gadget id="calculator">5 / 100</gadget>
<output>1/20 = around 0.05</output>

<gadget id="calculator">500 * (1/20)</gadget>
<output>25</output>

<result>25</result>