If the personal monthly income is between 1,600 and 2,100 yuan, the part exceeding 1,600 yuan will be subject to personal income tax at a rate of 5%. Fangfang's father has a monthly income of 1,800 yuan, how much personal income tax should he pay?
如果个人月收入在1600～2100元之间，超过1600元的部分就按5%的税率缴纳个人所得税．方方的爸爸月收入1800元，他应缴纳个人所得税多少元？
<gadget id="calculator">1_800 - 1_600</gadget>
<output>200</output>

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

<gadget id="calculator">200 * (1/20)</gadget>
<output>10</output>

<result>10</result>