On January 1, 2002, class 61 deposited 500 yuan in current savings in the bank. If the annual interest rate is 0.99%, how much is the total amount of principal and after-tax interest after half a year?
六1班2002年1月1日在银行存了活期储蓄500元，如果年利率是0.99%，存满半年时，本金和税后利息共是多少元？
<gadget id="calculator">0.99 / 100</gadget>
<output>0.0099</output>

<gadget id="calculator">500 * 0.0099 * 0.5</gadget>
<output>2.475</output>

<gadget id="calculator">20 / 100</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 - (1/5)</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">2.475 * (4/5)</gadget>
<output>1.98</output>

<gadget id="calculator">500 + 1.98</gadget>
<output>501.98</output>

<result>501.98</result>