In 2008, when Uncle Li's deposit expired, the total interest was 1680 yuan. At that time, the bank's deposit interest was subject to 5% interest tax. How much interest tax does he have to pay?
2008年，李叔叔的一笔存款到期后，共有利息1680元，当时银行的存款利息需缴5%的利息税．他需缴多少元利息税？
<gadget id="calculator">5 / 100</gadget>
<output>1/20 = around 0.05</output>

<gadget id="calculator">1_680 * (1/20)</gadget>
<output>84</output>

<result>84</result>